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SANITAEY AND APPLIED CHEMISTET 



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A TEXT-BOOK OF 
L SANITARY AND APPLIED 
*' " CHEMISTRY 

OB 

THE CHEMISTRY OF WATER, 
AIR, AND FOOD 



BY 

E. H. S. BAILEY, Ph.D. 

PROFESSOR OF CHEMISTRY, UNIVERSITY OF KANSAS 



Ntfo fforft 
THE MACMILLAN COMPANY 

LOHDON: MACMILLAN & CO., Ltd. 
1906 

All rights reserved 



LIBRARY of CONGRESS 
Twn Cooics Received 

JUL 18 1906 

PCtfjyrieht Entry 
KSS/fU XXc, No. 
COPY B. ' 




COPYRIGHT, 1906, 

By THE MACMILLAN COMPANY. 






is 



Set up and electrotyped. Published July, 1906. 



NortoooU $r«8 

J. S. Cushing & Co. — Berwick & Smith Co. 

Norwood, Mass., U.S.A. 



PKEFACE 

The object of this work is to furnish a text-book upon 
applied chemistry that is suitable for use by those students 
who have had a course in general chemistry, such as is 
usually completed in a good high school or in the earlier 
years of a college course. The particular phase of applied 
chemistry treated is that which pertains to the daily life 
of the household, but the subjects considered do not by any 
means cover the whole field of what might be called chem- 
istry applied to daily life, but only the most important 
topics. 

Although primarily intended for use as a text-book, much 
scattered material is here collected from Government Ee- 
ports and elsewhere, so that it is believed the book will 
prove valuable for general information and reference. The 
difficulty of condensing, without sacrificing something in 
clearness, is thoroughly recognized. 

Some simple reactions in general and organic chemistry 
have, it is true, been introduced, but it is believed that they 
are of a kind to be readily understood by students, with a 
little explanation from the instructor. It would be well to 
supplement the text by lectures on the topics studied and 
also to give time for discussions. 

The author believes that a practical method for teaching 
the subject, if a sufficient number of books of reference are 
at hand, is to outline topically the subject to be studied and 
require a preparation on those topics from the student. 

It has been the intention of the author to introduce 



VI PKEFACE 

enough facts to render the subject intelligible and readily 
comprehended, and not to burden the pages with details 
which belong properly to a more voluminous treatise on 
the subject. 

One of the most important features of the book is the 
introduction of experiments, which are distributed through- 
out the text and which it is believed will very materially 
aid the instructor who may have occasion to direct the work 
of the students. These experiments are suggested by several 
years of experience with classes in Sanitary and Applied 
Chemistry, and they are of such a character as can be per- 
formed in any chemical laboratory and with a moderate 
amount of inexpensive apparatus. More difficult experi- 
ments, which would involve a knowledge of quantitative 
analysis, have been purposely omitted. The instructor can 
add more experiments, if sufficient apparatus is at hand and 
the time allotted to the course will permit. 

The first part of the book is devoted to water, air, heat- 
ing, lighting, and ventilation, — to those practical problems 
with which we come in contact every day ; and the second 
part is occupied with a discussion of foods and beverages. 
In the latter section, although many adulterants are pointed 
out and the simpler tests for them are given in the experi- 
ments, no attempt is made to do the work, which properly 
belongs to the trained microscopist or analytical chemist. 

For many valuable suggestions, which were made while 
the book was going through the press, and for assistance in 
reading proof, the author is especially indebted to Professor 
J. T. Willard, Dr. James Naismith, Professor Isabel Bevier, 
Professor M. A. Barber, Dr. H. P. Cady, Dr. W. D. Bigelow, 
Professor W. C. Hoad, and Mrs. A. T. Bailey. 



CONTENTS 

PAGE 

Introduction xix 

PART I 

SANITARY CHEMISTRY 

CHAPTER I 

The Atmosphere 

History — Proof that air has weight — Experiments of Galileo, 
Torricelli, and Lavoisier — Experiments by Cavendish and 
by Bunsen, Leroy, and Regnault — Recent discoveries by 
Ramsey and Rayleigh — Methods used for detecting argon 
and helium — Composition of the air — Experiments to illus- 
trate composition of air — Proof that air is a mechanical 
mixture — Methods used for analysis of air — Oxygen in 
expired air — Moisture in the atmosphere — Proof that moist 
air is lighter than ordinary air — Experiments illustrating 
the presence of moisture in air — Carbon dioxid in free air 
and in closed rooms — Effect of impure air upon the system 
— Experiments to show the amount of carbon dioxid in the 
air — Nitric acid, ammonia, and other impurities in the 
atmosphere — Ozone and its properties — Experiments upon 
ozone — The effect of carbon monoxid upon the system — 
Substances in suspension in the air — Methods of studying 
the dust of the atmosphere — Bacteria in city air — Micro- 
organisms not abundant at great altitudes — Infectious 
diseases readily propagated by dust — Arsenic in the air — 
Experiments to show presence of arsenic in papers and 
fabrics — Injurious trades — Composition of ground air — 
Source of the impurities in ground air — Effects of ground 

air upon the system — Offensive gases 1 

vii 



Vlll CONTENTS 

CHAPTER II 
Fuels 

PAGl 

Combustible elements in fuels — How heat is produced by com- 
bustion — Cellulose, the basis of ordinary fuels — Wood as 
fuel — Amount of water in different woods — Effect of dry- 
ing upon wood — Composition of wood ashes — Charcoal — 
Method of making charcoal — Peat — Occurrence and prepa- 
ration — Coal — Characteristics of different kinds of coal — . 
Composition of different coals ■ — The analysis of coals — 
Natural and artificial gases as fuel — Advantages of gas as 
fuel — Burners used with gas — Composition of natural gas . 23 

CHAPTER III 
Heating and Ventilation 

Common methods of heating — Use and economy of the fireplace 

— The stove as a heating device — Use of the hot-air furnace 

— Use of steam with direct and indirect radiation — Advan- 
tages of hot- water heating — Electricity as a source of heat 

— Ventilation — Why little attention is paid to this subject 

— Necessity for ventilation — Amount of air used up in respi- 
ration — Contamination of air by lights — Properties of im- 
pure air — Amount of fresh air necessary to health — Crowd 
poisoning — Conditions necessary for good ventilation — 
Mechanical system of ventilation — Devices used for venti- 
lating ordinary rooms — Experiments upon air currents and 
temperature 33 

CHAPTER IV 

Lighting 

Sources of artificial light — Solid, liquid, and gaseous light-pro- 
ducing substances — The candle flame — Experiments with 
the candle flame — Use of gas for illuminating purposes — 
History of the development of artificial light — Candles as a 
source of light — Composition of candles — Method of mak- 
ing candles — Use of kerosene for lighting — Sources of coal 



CONTENTS IX 



oil and method of making — Distillates from Pennsylvania 
petroleums — Adulteration of kerosene — Experiments to 
show the flash point of oils — History of illuminating gas — 
Method of making gas — By-products in gas manufacture — 
Method of making water gas and its properties — Preparation 
and properties of air gas — Pintsch gas — Calcium carbid 
and its use in making acetylene — Composition of illuminat- 
ing gases — Experiments upon coal gas — Experiments upon 
acetylene gas — Lamps used for the burning of oils — Incan- 
descent gas lights — Method of making mantles and their 
composition — Advantages of incandescent lights — Electric 
lights — The ideal light of the future . . . . . 46 

CHAPTER V 

Water 

Impurities in water — Source of impurities in water — Character 
of rain, river, lake, and well waters — Mineral waters — Ex- 
periments upon mineral substances in water — Hard waters 

— Disadvantages of the use of hard water — Experiments 
on hard water — Organic impurities in water — Source of 
these impurities — The sanitary analysis of a water — Mean- 
ing of the presence of free ammonia, albuminoid ammonia, 
nitrates, nitrites, and chlorin in a drinking water — Experi- 
ments to determine the quality of water — Analysis of city 
water supplies — Table — Drinking water and disease — Effect 
of suspended matter in water — Organic impurities in water 
— Illustration from the city of Massina — Illustration from 
the Valley of the Tees, England — Illustration from Plym- 
outh, Pennsylvania — Illustration from Hamburg, Ger- 
many — The cause of pollution of ordinary wells ... 61 

CHAPTER VI 
Purification of Water Supplies 

Method of purifications by sedimentation, dilution, and oxidation 

— Eiltration by the English filter bed system — Mechanical 
filtration — Clark's process — Household filtration — Storing 
ground water — Effect of freezing upon water . . . 79 



X CONTENTS 

CHAPTER VH 
Sewage : Disposal of Household Waste and Garbage 

PAGB 

Composition of sewage — Oxidation of sewage — Modern theories 
for purification of sewage — Disposal of sewage by dilution 

— The sewage of Milwaukee and Chicago — Disposal of 
sewage by irrigation — Intermittent filtration — The septic 
tank — Precipitation of sewage — Disposal of household 
waste — The use of the stove or furnace for disposal of waste 

— Burying in the soil — Methods used for disposing of waste 
in large cities — Cremation as used abroad — "Reduction" 

of garbage and utilization as a fertilizer .... 84 

CHAPTER Vm 
Cleaning: Use of Soap and Bluing 

Necessity for cleanliness — Cleaning materials act mechanically 
or chemically — Polishing powder — Borax — Ammonia — 
Cleaning leather, wood, etc. — Solvents for grease — Cleaning 
marble — Use of solvents upon household fabrics — Removal 
of grease by blotting paper, French chalk, fuller's earth — 
Treatment of paint spots with oil and turpentine — Sugar 
and acid spots — Ink spots — To clean tarnished silver — 
Cleaning polished brass and copper — Experiment to remove 
iron rust 92 

Soap : History of the discovery of soap — Raw material used in 
its manufacture — Process of saponification — Method of 
making soap commercially — Mottled, toilet, transparent, 
and perfumed soaps — Scouring soaps and their use — Soft 
soap — No economy in the use of a cheap soap — Advantage 
of a well-dried soap — Theories in regard to the action of 
soap — The use of hard water — Experiments upon making 
soap and in testing its composition — Washing soda — Ex- 
periments to test a washing powder 96 

Bluing : Use of indigo — Prussian blue for making liquid blue — 
Ultra marine and its use as a bluing material — Experiments 
with Prussian blue and with ultra marine — Aniline colors 
as used in liquid blues ........ 108 



CONTENTS XI 

CHAPTER IX 

Disinfectants, Antiseptics, and Deodorants 

page 
The necessity for using disinfectants and antiseptics — The im- 
portance of the sense of smell — Tests for disinfectants — 
How bacteria multiply — An ideal disinfectant — Use of the 
following disinfectants and antiseptics : Sunlight — Dry air 

— Dry earth — Charcoal — Experiments upon the action of 
animal charcoal — Dry heat and its use — Sulfur dioxid 
as a disinfectant — Carbolic acid and its value — Copper sul- 
fate — Iron sulfate — Zinc chlorid — Potassium permanga- 
nate — Fire the most effective means of destroying disease 
germs — Steam as used for destruction of germs — Boiling 
water and how it may be used — Chlorid of lime, its value 
and use — Formaldehyde gas and the method of applying it 

— Corrosive sublimate and its value as an antiseptic . . 106 



PART II 

CHEMISTRY OF FOOD 

CHAPTER X 

Food 

Definition of food — Distinction between food and medicine — 
Uses of food — Delicacy of the sense of taste — Experience 
has been our guide in selecting food — Variety of food — 
Value of a mixed diet — Selecting food suited to habit and 
employment — Reasons for cooking foods — Food used to 
build up the tissues and supply energy — Synthetic foods — 
Elements contained in the body — Amount of substances 
occurring in the body — Carbohydrate and nitrogenous foods 
— The cellulose, cane sugar, and glucose groups — Proximate 
substances contained in foods, viz. water, fat, carbohydrates, 
protein, organic acids, and mineral salts . . . .117 



Xll CONTENTS 

CHAPTER XI 
Cellulose, Starch, Dextrine, Legumes 

PAGE 

Occurrence of cellulose and its properties — Experiments upon 
cellulose — Sources of starch and amount found in various 
cereals — Wheat, its composition — Comparison of different 
grades of wheat — The composition and properties of wheat 
flour — Analysis of different kinds of flour — Milling prod- 
ucts of flour — Corn — Composition, properties, and uses — 
Comparison of wheat and corn — Oats — Composition and 
peculiar characteristics — Rye — Its source, composition, 
and use — Barley — Its composition — Rice — Its cultiva- 
tion, composition, and properties — Potatoes — History 
of the introduction of potatoes — Composition and value of 
potatoes — This tuber not suited for use as a staple article 
of diet — Composition of sweet potatoes — Cassava (tapioca) 
— Its source and method of manufacture — The source and 
method of preparing arrowroot — Properties of other starches, 
sago, tons les mois, etc. — Adulteration of starch and method 
used for the detection of adulteration — Legumes — Cultiva- 
tion of the members of the Pulse Family — Properties of 
the legumes — Composition of peas, beans, and lentils — 
Experiments upon legumes — Value of legumes as a food — 
Bananas — Starch — Sources of commercial starch and 
method for making — Experiments upon starch — Dextrine 
and method of making — Gums — Inulin — Physical proper- 
ties of starch — Experiments with starch grains — Chem- 
ical properties of starch — Experiments in making starch 
and to show its properties — Experiments upon dextrose — 
Experiments with diastase 126 

CHAPTER XII 

Bread 

Primitive method of making bread — Two general methods of 
making dough light — First, non-fermentation method ; sec- 
ond, fermentation method — Bread not raised with fermen- 
tation : by the use of eggs, alcoholic liquors, ammonium 
carbonate, baking soda, baking soda and molasses, carbon 



CONTENTS Xiil 

PAGE 

dioxid, baking soda and hydrochloric acid, baking soda 
and sour milk, baking soda and cream tartar — Baking 
powders — Cream tartar powders — Phosphate powders — 
Alum powders — Experiments with baking powders — 
Bread raised by fermentation: first, by use of yeast; 
second, by use of leaven ; third, by the salt-rising process 

— Composition and properties of yeast — Method of mak- 
ing yeast — Theory of use of leaven — What takes place in 
the salt-rising process — Chemistry of the fermentation of 
dough — Essentials to be noted in making good bread — 
Construction and use of the oven — Temperature used in 
baking — Difference between fresh and stale bread — 
Amount of bread that can be made from a given weight 
of flour — Composition of different kinds of bread — Dif- 
ference between the crumb and crust — Starch alone will 
not sustain life — Value of a mixed diet to man — Bread a 
nutritious food — Value of white vs. whole-wheat bread — 
Patent flour — Stale bread and why it is wholesome — Corn 
bread — Why some bread is bad — Adulteration of flour and 
bread — Use of copper sulfate to make bread white — Use of 
alum as an adulterant — Experiments upon copper sulfate in 
bread — Experiments to detect alum — Occurrence of ergot 

in flour 164 

CHAPTER XIII 

Breakfast Foods and Other Special Foods 

Breakfast foods and their composition — Conclusion in regard to 
the use of breakfast foods — Foods for infants and invalids 

— Macaroni, vermicelli, etc., as foods — Composition of 
macaroni 180 

CHAPTER XIV 
Sugars 

History and classification — Consumption of sugar in different 
countries — Different sugars known to the chemist — Classi- 
fication of sugars — The sucrose and glucose groups — 
Members of the sucrose group — Sources of cane sugar — 
The sugar cane as a source of sugar — Cultivating the sugar 



XIV CONTENTS 

PA.cn 

cane — Extraction of the juice — Purification of the juice by 

the use of sulfurous acid — Concentration of the juice in 
the "triple effect" and in the vacuum pan — Use of the 
centrifugal — Treatment of the sirup — Making sugar from 
the sugar beet — History of the development of the industry 

— Use of the diffusion process — Concentration and purifica- 
tion of the juice — Manufacture of maple sugar — Adultera- 
tion of maple sugar — Sorghum sugar and its manufacture 

— Molasses — Sugar-refining — Methods adopted in the com- 
mercial centers — Use of the bone-black filter — Revivifying 
bone black — Use of the vacuum pan and centrifugal — 
Granulated sugar — Powdered and cube sugar — Experiments 
to show the properties of sugar — Composition of raw 
and of refined sugars — Food value of sugars — Maltose, its 
source and properties — Lactose, method of making and 
properties 185 

CHAPTER XV 
Glucose or Grape-sugar Group 
Processes used for the manufacture of glucose and its composi- 
tion — Uses of glucose — Healthfulness of the product — 
Experiments upon glucose — Invert sugars — Levulose — 
Honey — Composition and properties of honey — Experi- 
ments with honey 200 

CHAPTER XVI 
Leaves, Stalks, Roots, etc., used as Food 
Value of this class of nutrients — Carrots, parsnips — Turnips 
and beets — Leaves as food — Composition and value of cab- 
bage— Greens — ■ Asparagus — Rhubarb, etc. — The use of 
onions and leeks — Tomatoes and their use .... 207 
Irish moss and its composition — Mushrooms and toadstools — 
The growing of mushrooms and their composition — The 
selection of the non-poisonous varieties . . . .210 

CHAPTER XVII 
Composition and Food Value of Fruits 
Some definitions — Composition of fruit at different periods of 
growth — Change in composition as illustrated by analysis 



CONTENTS XV 

FACHI 

of apples —The ripening of fruit — Table showing composi- 
tion of various fruits — Value and properties of the different 
ingredients in fruits — Malic acid, citric acid, tartaric acid 
with experiments — Effect of cooking upon fruits , . 212 
Jams and jellies and their adulteration — Opportunity for falsifi- 
cation in this material — Substitutes for jam and jelly upon 
the market — Experiments upon adulterated jellies — Fruit 
sirups — Flavoring extracts 219 

CHAPTER XVni 

Edible Fats and Oils — Food Value of Nuts 

Composition of edible fats — Digestion of fats and oils — Amount 
of fat in different vegetable and animal substances — Use of 
cotton-seed oil in cooking — Use of oil of cocoanut — Lard — 
Method of making the different grades, such as refined lard, 
kettle-rendered lard, neutral lard — Adulteration of lard — 
Manufacture of compound lard, cottolene, cottosuet — Use 
of nuts as food — Composition of the more important nuts — 
Removal of excess of oil from some varieties — Value of 
almonds for food — Use of peanuts as food .... 223 

NITROGENOUS FOODS 

CHAPTER XIX 

Meat 

Concentration of nitrogenous food by animals — Importance of 
nitrogen in the animal body — Classification of nitrogenous 
bodies — Functions of albuminous substances — Structure of 
lean meat — Constituents of meat — Composition of beef — 
Use of animal food in different countries — Cooking of meat 
by roasting, broiling, etc. — Beef extracts and their value — 
Different kinds of meat similar in composition — Fish as a 
cheap and nutritious food — Characteristics of this food — 
Fat and lean fish — Use and food value of oysters — Danger 
from trichina, tapeworms, etc., in pork — Experiments upon 
cooking meat . 228 



XVI CONTENTS 

CHAPTER XX 

Eggs 



Pi.GB 



Composition of egg white and egg yolk — Use of eggs as food — 
Methods of preservation — Desiccated eggs — Proper method 
for cooking eggs — Experiments with egg white and egg yolk 238 

CHAPTER XXI 

Milk, Cheese, and Butter 

Composition of milk of different animals — Composition of vari- 
ous kinds of milk — Experiments upon the specific gravity 
of milk — Composition of butter fat and method for its de- 
termination — Use of koumiss — Experiments to determine 
amount of butter fat and total solids — Cause of the souring 
of milk — Experiments with coagulents — Methods of raising 
cream — Sterilized and pasteurized milk — Condensed milk 

— Its composition — Nature of modified milk and how it 
is prepared — Experiments to detect milk adulteration — 
Cheese — The method for its manufacture — Description of 
different kinds of cheese — Table showing composition of 
various cheeses — Butter and butter substitutes — Conditions 
necessary for making good butter — Renovated or process 
butter — Manufacture of oleomargarin — Materials used in 
making oleomargarin — Attitude of the government toward 
this industry — Experiments with butter .... 242 

CHAPTER XXH 

Non-alcoholic Beverages 

General demand for beverages of this class — Amount of tea, 
coffee, and cocoa used in the United States — Source of tea 

— Composition of green and black tea — The most important 
constituents and their properties — Experiments upon mak- 
ing a decoction of tea and its properties — Paraguay tea — 
Coffee-leaf tea — Coffee — History of its growth — Method 
of cultivation and preparation of the berry — Analysis of 
coffee — Effect of roasting — Adulteration of ground coffee 

— How to make the beverage — Coffee substitutes — Cocoa 
and chocolate — History of this product — Method of grow- 



CONTENTS XV11 

PAGE 

ing the nuts — Composition of chocolate, cocoa, cocoa shells 

— Value of cocoa as a food material — Manufacture of choco- 
late — Experiments upon chocolate — The cola nut — Com- 
parison of the effect of the non-intoxicating beverages upon 

the system 257 

CHAPTER XXIII 

Alcoholic Beverages 

Use of alcohol from the earliest history of the world — Properties 
of alcohol — Consumption of alcoholic liquors in different 
countries — Classification of alcoholic beverages into fer- 
mented, malt, distilled liquors, and cordials — Per cent of 
sugar in different fruits — Wine — Source of wine — Method 
of making — Fermentation — Aging wine — Chemical reac- 
tion involved in wine making — Changes produced by aging 

— Composition of various wines — Classification of wines — 
Why grapes make better wines than other fruits — Adultera- 
tion and plastering of wines — Diseases of wines — Experi- 
ments upon wine — Cider — Method of making — Adulteration 
and falsification — Beer — Method of making malt — Chemi- 
cal changes involved in manufacture of beer — Composition 
of some malted liquors — Experiments upon beer — Distilled 
liquors — Definition — Method of making alcohol — Distinc- 
tion between brandy, whisky, rum, and gin — Adulteration 
of fermented liquors — Liqueurs — Cordials — Physiological 
action of alcohol 271 

CHAPTER XXIV 

Food Accessories 

Difference between condiments and spices — Common adulterants 
of ground spices — Source and properties of cloves, cinna- 
mon, pepper, ginger, nutmeg, mustard — Experiments upon 
spices — Vinegar — Chemical changes involved in its manu- 
facture — Material used, such as wine, fruit spirits, malt, 
etc. — Quick vinegar process — Experiments upon vinegar 

— Salt — Occurrence of salt in different parts of the world 

— Method of obtaining the commercial salt — Composition 

of average samples — Uses of salt 288 



XV111 CONTENTS 

CHAPTER XXV 
Preservation of Foods — Coloring of Food Products 

PAGE 

Method of preservation of food formerly adopted and those in 
use at present time — Conditions favoring fermentation and 
decay — Preservation by canning — Canning as carried on 
in large manufactories — Experiments upon preservation of 
food — Use of tin cans — Experiments upon the composi- 
tion of the can — Recent use of chemical preservatives — 
Objection to the use of these substances — Use and method 
for detection of borax, sodium benzoate, salicylic acid, 
sodium sulfite, and formaldehyde — Coloring of food prod- 
ucts — Objections to this custom — Use of copper to give a 
green color to pickles — Experiments upon food coloring . 297 

CHAPTER XXVI 

Economy in the Selection and Preparation of 
Food — Dietaries 

Proper methods for cooking food — How starch is affected by 
heat — Changes which fats undergo in cooking and the effect 
of heat upon them — Leguminous foods and how they should 
be cooked — A large amount of nutriment at small cost — 
Comparison of vegetable and animal foods — Relation be- 
tween cost of the food and its nutritive value — Importance 
of cooking each food in the best way — The use of a steam 
cooker in economizing fuel — The Aladdin oven as an eco- 
nomic kitchen utensil 308 

Dietaries : Histoiy of the study of the composition of food — 
Experiments carried on by the United States government 
— Definition of calories — Fuel value of different classes of 
nutrients — Use of the respiration calorimeter — A study of 
the food of different individuals or classes — Table showing 
dietaries used in the United States and abroad — Standard 
dietaries as estimated by different authorities — The use of 
smaller amounts of proteids than the accepted dietary would 
indicate — The ideal ration — Cost of food and nutritive 
ratio — Per cent of income expended for food by people of 
different classes 312 

Bibliography 323 



INTRODUCTION 

A knowledge of the science of chemistry is necessary 
for a proper understanding of so many of the other sciences 
that it is not strange that this subject is so often required of 
students in the lower grades. To know even the rudiments 
of physics, botany, biology, geology, mineralogy, or physi- 
ology, the student must have a fair knowledge of chemistry. 

When we consider, however, the arts that have to do with 
modern living, — the eating, drinking, and breathing, all of 
which may be prosaic enough in their way, — it is evident 
that the foundation study here also is a knowledge of the 
composition of the substances surrounding us. 

A knowledge of the relations to health of pure air, un- 
polluted water, and wholesome food will have much to do 
with improvement in sanitary conditions, not only of stu- 
dents themselves, but, through them, of the people at 
large. The air is usually said to be free, but pure air and 
sunshine cost money as the crowded tenements show. The 
best lighted and ventilated rooms are worth the most. 
Since physicians agree that impure air is a predisposing 
cause of a large per cent of diseases, it is of the greatest 
importance that a knowledge of the danger from this source 
be diffused among all classes of people. 

Water is furnished by the well or cistern at the farm or 
the isolated country house, and for a very large population 
by a corporation or by the municipality itself. Those who 
use the water from the private source of supply or those 
who furnish it to the multitude of the city, should know 

xix 



XX INTRODUCTION 

how water becomes polluted and how to guard against 
disease from this source. 

The food supply is obtained from various sources. There 
is a growing tendency to have food prepared outside the 
household, and the family learn to depend on the baker, the 
grocer, and the packing house for their food. With this 
tendency comes the temptation to those who furnish food 
ready prepared or dressed, to falsify or adulterate it, be- 
cause they have the opportunity. 

It is certainly time that the people should have some 
practical knowledge of food and medicine. Without this 
knowledge they will continually be imposed upon by 
those who have something to sell which may be worthless 
as a food, or dangerous as a medicine. 

Just as society claims the right to protect itself against 
epidemics, against polluted water, and against smoke nui- 
sances, so it is learning that it also has the right to protect 
itself against bad food. The United States and the various 
state and city governments have aided the people generously 
for the past twenty-five years, and by their published analy- 
ses, bulletins, and other literature have assisted notably in 
molding public sentiment in favor of wholesome and un- 
adulterated food. The foundation of the present move- 
ment seems to be publicity. 

Schools and colleges are beginning to see their oppor- 
tunity to impart a kind of knowledge that is practical and 
sane, and so we have the manual training school and the 
agricultural college, as well as instruction in domestic 
science in schools of a lower grade. 

A thorough understanding of the facts of applied chem- 
istry will not make the skilled workman, nor will the theories 
of chemistry make the accomplished cook, but a broad and 
thorough knowledge of the underlying principles will go 
very far toward developing common sense in hygiene and 
in the selection and preparation of food. 



SANITAKY AND APPLIED CHEMISTEY 



PAKT I 

SANITARY AND APPLIED CHEMISTRY 

CHAPTER I 

THE ATMOSPHERE 

HISTORY 

The early philosophers in the time of Aristotle, 350 B.C., 
thought there were four elements, — earth, air, fire, and 
water, — and that each of these had special properties, and 
they also believed that the air had weight. For sixteen 
hundred years comparatively nothing was done except to 
theorize in regard to the properties of air. Then Galileo, 
an Italian, showed that a copper globe filled with air under 
ordinary pressure weighed less than the same globe filled 
with compressed air. Galileo was fortunate in making the 
acquaintance of Torricelli, and at the death of the former, 
Torricelli carried on the experiments. He explained why 
it was impossible to raise water more than thirty-three feet 
in a tube by suction ; that is, that there was not sufficient 
pressure of the air to force the water higher, and he also 
reasoned that a heavier liquid, like mercury, could not be 
raised as far as water by suction. He tried this experiment 
and found that mercury could be raised only about thirty 
inches, and noticed that the relation between the specific 
gravity of mercury and that of water was inversely propor- 
tional to the height to which the two liquids could be raised. 
That is, water can be raised 13.6 times as far as mercury. 

B 1 



2 SANITARY AND APPLIED CHEMISTRY 

The theory that air had weight, and kept the mercury or 
the water up in the barometer tube, was not fully adopted 
when Torricelli died. Pascal, who followed these inves- 
tigators, said that if their theory was true, a column of 
mercury would fall when a barometer was carried to an 
elevation, so he secured the services of a friend to carry a 
barometer to the top of a mountain in France, and the latter 
was delighted to find that as he ascended the mountain the 
mercury fell. It was left to Boyle to use this apparatus, 
which he called a "barometer" (Gr. baros, metron), to 
measure the weight of the air. 

All this time air was regarded as a simple element, and the 
next epoch in its study was the discovery, by Priestley and 
Scheele in 1774, that it contained the element oxygen. It 
was left for the French chemist, Lavoisier, to correlate the 
discoveries of several chemists, and to show that when 
oxygen was taken out of the air, the gas that remained was 
the so-called nitrogen, discovered in 1772 by Rutherford. 
Lavoisier found that by heating mercury in a confined 
volume of air, it would take up a measured quantity of 
oxygen, and the residual gas left in the flask, which would 
not support combustion, was nitrogen. Cavendish made a 
large number of experiments on the air, but it was Bunsen, 
Le Roy, and Regnault who showed that air is not always 
of the same composition, though very nearly so, and that 
consequently it cannot be a chemical compound, but must 
be a mixture of different gases. These experiments, made 
about the middle of the last century, marked another im- 
portant period in the study of the atmosphere. 

The last era is the recent discovery (in 1895 and the years 
following), by two Englishmen, Lord Rayleigh and Pro- 
fessor Ramsay, of argon; and later helium and other gases 
were discovered in the atmosphere. The circumstances that 
led to the discovery of argon are interesting. Lord Rayleigh 



THE ATMOSPHEKE 3 

noticed that the weight of a liter of nitrogen obtained 
from chemicals, as when ammonium nitrite is heated, 
is 1.2505 grams, while that obtained from nitrogen of the 
air is 1.2572 grams. It was impossible to account for this 
by assuming errors in the weighings, which were made with 
exceptional care. These men experimented with air by 
passing a strong electric spark through a confined volume 
of air, contained in a tube over mercury, thus causing some 
oxygen and nitrogen to unite, and forming an oxid of nitro- 
gen. The latter was absorbed by a solution of potassium 
hydroxid, then more oxygen was introduced, and the spark- 
ing by electricity was continued, until finally only a small 
residue remained, which could not be made to combine with 
oxygen. The excess of oxygen was then absorbed, and the 
residual gas was placed in a Plticker tube under dimin- 
ished pressure, and, while a current of electricity was 
passed through it, was examined by means of the spectro- 
scope. The spectrum was different from that of any known 
gas. Other substances were brought in contact with this 
gas, but it did not unite with them, and the name " argon," 
which signifies " inactive," was given to the gas. This gas 
was also prepared from air, after the oxygen had been 
removed, by passing it over red-hot magnesium, which 
took out the nitrogen and left the argon. 

A little later, the element "helium" was found first in 
the mineral Clevite, and afterwards in the air. This had pre- 
viously been discovered in the atmosphere of the sun by the 
examination of sunlight with a spectroscope, and chem- 
ists were delighted to find that the gas which they obtained 
from certain minerals, and also from mineral springs, was 
the same as had previously been discovered in the sun. 
More recently the other gases, neon, krypton, xenon, were 
discovered. Since liquid air can now be made at a compara- 
tively small expense in large quantities, these latter gases 



4 SANITARY AND APPLIED CHEMISTRY 

may be separated from it by " fractional distillation," and 
may thus be more thoroughly studied. 

CONSTITUENTS OF THE AIR 

The average composition of moist air by volume is as 
follows : — 

Parts per 1000 

Oxygen 207.7 

Nitrogen . . . . . . . . 773.5 

Water 8.4 

Argon . 9.4 

Carbon dioxid .3 to .4 

Nitric acid Trace 

Ammonia Trace 

Hydrogen snlfid ....... Trace 

Sulfurous anhydrid Trace 

Helium TUtfW^ 

Krypton xinrfonnF 

Xenon aooAooo 

Hydrogen ^ 

Neon TlrtW 

Experiment 1. To show the weight of air. Fill a glass 
tube about 900 mm. long, closed at one end, with clean, dry 
mercury, and invert it over a vessel of mercury. Read the 
height of the column by means of a meter measure. 

Note. If a sufficient quantity of mercury is not at hand, this and 
Experiment 3 may be performed by the instructor only. 

Experiment 2. Eead a good barometer, and compare 
reading with that obtained in the tube. 

Experiment 3. To show the effect of moisture in air, or 
the vapor tension of water, add a small drop of water to the 
mercury, by putting it beneath the surface of the mercury 
in the tube, with a glass tube bent upward at the lower end, 
Record the difference of level. 



THE ATMOSPHERE 5 

Experiment 4. To prove the composition of air, melt 
some phosphorus in one end of a 100 cc. eudiometer tube 
tightly closed with a soft cork. The phosphorus may be 
melted by immersing the end of the tube in boiling water 
for a few minutes. Throw the phosphorus along the tube 
by swinging it, and it should take fire. Immerse the corked 
end of the tube in a cylinder of water, remove the cork, and 
the water will rush in. When the contents of the tube has 
become of the same temperature as the air, read the level 
of the water inside the tube, first making it of the same 
height inside as outside, by lowering or raising the tube. 
Calculate the per cent of oxygen in the air. 

As previously stated, these gases, oxygen, nitrogen, etc., 
are mechanically mixed in the air. This may be proven as 
follows : — 

1st, Because the air in different localities has different 

composition. 
2d, Because air dissolved in water is richer in oxygen 

than ordinary air. 
3d, Because the mixture of oxygen and nitrogen in the 

proportion of air cannot be made to combine by a 

spark to form air. 
4th, If liquid air is allowed to evaporate, the nitrogen 

goes off first, leaving nearly pure oxygen. 

Air is vitiated or rendered too impure for respiration 
from a variety of causes. Among these may be mentioned 
an increase in the amount of carbon dioxid, and a conse- 
quent decrease in the amount of oxygen ; a lack of sufficient 
moisture, and an excess of moisture; by the presence of 
suspended impurities of a vegetable, animal, or mineral 
origin; by poisonous gases, from illuminating gas, sewers, 
or manufactories; by the presence of the impurities that 
are due to respiration, and by a mixture with ground air. 



6 SANITARY AND APPLIED CHEMISTRY 

The methods used for the analysis of air are usually 
volumetric. From a sanitary standpoint, the most practical 
thing is to determine the amount of some of the substances 
which are present in small quantity, but which are really of 
great hygienic importance. 

It is assumed that we are familiar with the properties of 
oxygen, a gas that assists in combustion, causes a spark to 
burst in a flame, and is absolutely necessary to respiration. 
The amount of oxygen found in the air in different localities 
varies, according to Bunsen, within narrow limits from 
20.97% to 20.84%. These results were confirmed by Reg- 
nault, R. Angus Smith, Leeds, and others, who made analy- 
ses of air from different parts of the world. In the crowded 
tenement districts the air has been found to contain as low 
as 20.60 % of oxygen. 

The air as it leaves the lungs contains about 79% of 
nitrogen and argon, and only 16 % of oxygen, for the air 
instead of containing the normal amount of carbon dioxid, 
now contains about 4.4 %. This oxygen has been consumed 
in the vital processes. When the normal proportions of 
the gases in the atmosphere are disturbed, the human sys- 
tem is very susceptible to it, and this is one of the causes 
for discomfort in a crowded room. 

Nitrogen, on the other hand, has properties that are, to 
some extent, opposed to those of oxygen. Nitrogen does not 
burn, does not support combustion, is not poisonous, and is, in 
fact, an inert gas. In combination, however, it is of special 
importance, as in nitrates, explosives, coloring matters, and 
alkaloids, as well as in vegetable substances, and in nearly 
all animal tissues. 

Water in the air is necessary both for the growth of 
vegetable and animal life. The amount of vapor that 
air holds in suspension depends, of course, upon the tem- 
perature. The higher the temperature, the greater the 



THE ATMOSPHERE 7 

amount of moisture the air will hold without precipitation. 
Where air contains as much moisture as, at a given temper- 
ature, it is capable of holding, it is said to be saturated. 
Humidity has reference not to the actual amount of vapor 
present, but to the proportion which this bears to the pos- 
sible maximum at that temperature. 

At 0° C, a cubic meter of air will hold only 4.87 g. of 
water; at 10° C, 9.92 g. ; at 15° C, 12.76 g. ; at 20° C, 
17.16 g. ; and at 32° C, 33.92 g. 

If the air is absolutely dry, plants wither and die, and 
animals do not thrive since they lose water too rapidly by 
its evaporation. The amount of moisture in the air varies 
from -g^th to ^To^k °^ the volume, and from 65 °J to 
75 °J of saturation is regarded as most beneficial to health. 
If the humidity of the air is 90 % of saturation, and the 
temperature is 90° F., the conditions are almost unbearable, 
while at the same temperature, with 50 °/ of humidity, it 
is not uncomfortable. Air that is saturated with moisture 
does not permit the heat of the earth to radiate so rapidly. 
At night, as the air cools, we get a deposit of dew. It is 
well to remember that the " dew-point " or the temperature 
at which a deposit of moisture begins varies with the amount 
of moisture in the air. The earth cools more rapidly on clear 
nights, hence in cold weather there is greater danger of frost. 
The amount of moisture thrown off from the lungs and skin 
is about one third of that taken in with the food. This would 
mean that from 1\ to 2 lb. of water would be given off per 
capita every 24 hours. Moist climates are adapted to the 
treatment of certain diseases, while we are familiar with 
the action of dry air, such as that of Colorado, Arizona, and 
California, in the treatment of tuberculosis. 

As air is essentially a mixture of one part of oxygen with 
four parts of nitrogen and a varying amount of water vapor, 
the weight of a liter of air would be equal to the sum of 



8 SANITARY AND APPLIED CHEMISTRY 

these constituents, and the way in which this weight will 
vary can be seen from the following figures : — 

The weight of a liter of nitrogen is . . . 1.25 grams 
The weight of a liter of oxygen is . . . 1.43 " 
The weight of a liter of water vapor is . .81 " 

From the composition of the air above noted, a liter of dry 
air would contain practically 

800 cc. of nitrogen weighing . . . 1.000 g., and 
200 cc. of oxygen weighing . . . .286 g. 

Giving a total weight of air as . . 1.286 g. 

Since water vapor is lighter than either nitrogen or 
oxygen, and since it displaces its own volume of these other 
gases, air containing water vapor will be lighter than an 
equal volume of dry air. 

To illustrate: Suppose we have a sample of air con- 
taining 5 % of water vapor, then a liter of this air would 
contain 

760 cc. of nitrogen weighing . . .950 g., and 
190 cc. of oxygen weighing . . . .272 g., and 
50 cc. of water vapor weighing . .0405 g. 

Total 1.2625 g. 

As the barometer is the measure of the weight of air, a 
column of moist air of a given height will weigh less than 
a column of dry air ; we say the barometer falls before a 
storm as there is more moisture in the air. It should 
be noted that the weight of the air at any time or place also 
depends on the temperature. 

Experiment 5. To show the presence of moisture in the 
air, fill a flask of about 1 liter capacity with pounded 



THE ATMOSPHERE 9 

ice or snow. Clean it thoroughly on the outside and 
wipe it dry. Suspend it in the room and notice after 
a short time the abundant deposit of moisture from the 
air. 

Experiment 6. Suspend two thermometers that read alike 
side by side on the iron stand in the laboratory. Make a 
note of the readings. Fasten about the bulb of one of them 
by means of a rubber band a wad of cotton that has been 
thoroughly soaked in water. Note after a short time the 
difference in temperature of the two thermometers. Will 
there be this difference if the air is absolutely saturated 
with moisture ? 

Carbon dioxid (C0 2 ) finds its way into the air : — 

1. By combustion. 

2. By respiration. 

3. By the decay of vegetable matter. 

4. By chemical action. 

5. By volcanic action. 

6. By the escape of ground air. 

This gas is not poisonous, as this term is ordinarily used, 
but animals may be said to drown in carbon dioxid gas. 
The amount of this gas in 1000 parts of air varies in dif- 
ferent places : for instance, in Munich it was found to be 
.051 ; in Scotland, .053 ; on London streets, .038 ; at Lake 
Geneva, .044. This is for the outdoor air. More recent 
investigations show that normal outdoor air contains between 
.03 and .04 parts of carbon dioxid. The air in crowded 
rooms is frequently extremely impure, as shown by the 
following analyses * : — 

iFox, u Sanitary Examination of Water, Air, and Food," p. 204. 



10 



SANITARY AND APPLIED CHEMISTRY 



CARBON DIOXID IN CLOSED ROOMS 



A schoolroom in England contained 

Sitting room in a private house 

Public library 

Courthouse gallery . 

Printing office 

Tailor's workshop . 

Boot and shoe finisher's shop 

Surrey Theater 

Standard Theater . 

Girls' schoolroom . 

Schoolroom in New York City 

Bedroom with closed windows 

Average of 339 experiments in mines 

Sleeping cabin of a canal boat 



Peecentage by Volume 
.241 
.304 
.206 
.290 
.149 
.306 
.528 
.218 
.320 
.723 
.280 
.230 
.785 
.950 



It is no doubt true that the amount of carbon dioxid in 
the air has something to do with the disagreeable sensations 
experienced in a crowded room. 

Some of these are : — 
Headache 
Stupor 

Eestlessness 

Craving for excitement 
Fainting 
Nausea 

Lowered Vitality. 

According to the experiments by Drs. Billings, Mitchell, 
and Bergay, it is shown that the disagreeable effects pro- 
duced upon the system by impure air are due to the fol- 
lowing causes: the reduction in the amount of oxygen, 
the increase of carbon dioxid, excess of moisture, the high 
temperature, the dust and disagreeable odors, in fact to all 
these combined. 



THE ATMOSPHERE 11 

We know that considerable pure carbon dioxid is not 
especially injurious, as workmen in breweries and other 
manufactories are not affected by even a larger amount of 
carbon dioxid than is found in the air of a crowded 
room. 

According to the experiment of Cowles and Feilmann, 1 
air that contains 14% of carbon dioxid and has remain- 
ing only 18.1% of oxygen, will extinguish a candle flame. 
In the absence of carbon dioxid air to which 22% of nitro- 
gen has been added will extinguish a candle flame. Ex- 
pired air has about the same composition as that produced 
by the burning of a candle in an inclosed space until the 
candle goes out. As an atmosphere, even as impure as this, 
could be breathed without causing insensibility, the common 
test for the air of a well, by letting down a burning candle. 
is within the limit of safety. 

For the determination of carbon dioxid, many forms of 
apparatus have been invented. Usually a measured amount 
of air is passed through a solution of barium hydroxid or 
calcium hydroxid, and the barium or calcium carbonate thus 
formed is filtered off and weighed. The reaction, where 
barium hydroxid is used, is as follows : — 

Ba(OH) 2 + C0 2 = BaC0 3 + H 2 0. 

Eather an ingenious apparatus is put upon the market espe- 
cially for the use of Boards of Health in testing the air 
of schoolrooms. This is known as Wolpertfs apparatus. 
The principle of this apparatus is the same as that pre- 
viously noted, except the amount of air is measured by a 
number of fillings of the bulb, and the density of the pre- 
cipitate by referring to a table gives an index to the amount 
of carbon dioxid. 

l Jour. Soc. Chem. Inch, Vol. 13, p. 1155 ; Vol. 14, p. 345. 



12 SANITARY AND APPLIED CHEMISTRY 

Experiment 7. To show the production of carbon dioxid 
by combustion, attach, a funnel, by means of a tube bent 
twice at right angles, like an inverted " D ," to a Woulf flask 
containing limewater. Through the other opening in the 
flask put a cork and glass tube, and aspirate air through the 
limewater. Place a lighted candle beneath the funnel, 
and notice the formation of carbon dioxid. Write the 
equation for the combustion of the carbon of the candle, 
and for the precipitation in limewater. 

Experiment 8. Eepeat the above experiment with a small 
jet of illuminating gas under the funnel, and notice whether 
the limewater becomes as quickly turbid as with the candle. 

Experiment 9. To show the presence of carbon dioxid in 
the breath, arrange an apparatus by the use of two Erlen- 
meyer flasks, fitted with corks, each provided with two holes 
fitted with glass tubes, so arranged that air may be drawn in 
through limewater in one flask at each inspiration, and may 
be passed out through limewater in the other flask at each 
expiration. Notice that the limewater is turbid in one 
flask and not in the other. Why ? 

Experiment 10. To determine the amount of carbon di- 
oxid gas in air, use Wolpert's apparatus, which depends 
on the turbidity produced by carbon dioxid in limewater, 
making tests in different rooms. 

Experiment 11. Determine the strength of a solution of 
limewater or baryta water against a standard solution of 
oxalic acid, containing 2.84 grams of oxalic acid per liter, by 
placing 25 cc. of limewater in a porcelain dish, and running 
into this, through a graduated burette, enough oxalic acid 
to exactly neutralize it, using a strip of turmeric paper as an 
outside indicator. This equation shows what takes place : — 

H 2 2 C 2 2 + Ca(OH) 2 = Ca0 2 C 2 2 + 2 H 2 0. 



THE ATMOSPHERE 13 

Find the exact capacity of a glass-stoppered bottle of 4-6 
liters capacity ; measure into this bottle 50 cc. of lime water, 
shake, and set aside for 6 or 8 hours. Take out with a 
pipette 25 cc. of the limewater without shaking, so as to 
get as little calcium carbonate as possible, and titrate this 
with the standard oxalic acid ; and the difference between 
the amount used and the amount required to neutralize 
25 cc. of the untreated limewater represents the effect due 
to the carbon dioxid gas in the air. The action of the carbon 
dioxid on the limewater is represented by the equation : — 

C0 2 + Ca (OH), = CaC0 3 + H 2 0. 

The oxalic acid used is of such strength that 1 cc. cor- 
responds to 0.5 cc. of carbon dioxid gas. Subtract 50 cc. 
from the capacity of the bottle for the space occupied by 
the limewater. Calculate the parts of carbon dioxid per 
10,000 parts of air. This may be reduced to standard con- 
ditions of temperature and pressure by the usual methods. 
(See " Public Health Laboratory Work," Kenwood, p. 194.) 

An example of the calculation is as follows : suppose it 
required 30 cc. of oxalic acid solution to neutralize 25 cc. 
of limewater, and the 25 cc. of limewater from the bottle 
of air is neutralized by, say, 27 cc. of the oxalic acid solu- 
tion. This means that the carbon dioxid in the air was 
equivalent to 3 cc. of oxalic acid solution. 1 cc. of this 
solution = 0.5 of carbon dioxid, then 3 cc. = 1.5 cc, which 
multiplied by 2 for the other 25 cc. of limewater in the 
bottle gives 3 cc. of carbon dioxid. If the capacity of the 
bottle was 4000 cc, subtract 50 cc. from this = 3950 = 
volume of the air taken. Hence we calculate .0759% of 
carbon dioxid in the air. 

Carbon monoxid (CO) is sometimes found in the air of 
inhabited rooms, on account of insufficient ventilation or 
leaky joints in furnaces. Red-hot cast iron will also trans- 



14 SANITARY AND APPLIED CHEMISTRY 

mit the gas. As it is extremely poisonous, — less than one 
half of one per cent in air being fatal to human life, — it is 
of the utmost importance that it be excluded from the air 
of our dwellings. Fortunately, although carbon monoxid 
itself has no odor, it is usually mixed with some other gas 
that has a decided odor. In coal gas it is mixed with the 
sulphur compounds which are so readily detected by smell, 
and in escaping furnace gases it is usually accompanied by 
sulfur dioxid, which has the familiar odor of a burning 
match. When formed by burning charcoal, there is scarcely 
a perceptible odor. (See Ventilation, p. 38.) 

Nitric acid in the air is largely a result of the oxidation 
of the ammonia. Some nitrogen oxids are formed -from 
free nitrogen by the lightning flashes in the air. The 
nitric acid, when washed into the soil by the rains, is of 
great value as a fertilizer for growing plants. 

Ammonia is formed partly by the decay of vegetable 
and animal matter in the soil and partly by other chemical 
processes. Ammonia would naturally unite with carbon 
dioxid, making ammonium carbonate, or with the nitric acid, 
making ammonium nitrate; and both the acid and the 
base in this latter salt are useful when washed down by the 
rain, in enriching the soil. The amount of ammonia varies 
from 0.1 to 100 volumes in a million volumes of air. 

Hydrogen sulfid will not ordinarily be found in pure air, 
but in cities, where there is decomposition of organic matter 
and sewer gas, it may be frequently detected by its disagree- 
able odor. Sulfurous anhydrid is not a constituent of the 
pure air of the country, but where soft coal is burned, or where 
there are manufactories operating, this gas will be found. 
Sulfur dioxid is quite noticeable in the vicinity of chemical 
works, especially where zinc, lead, and copper ores are smelted. 
An extremely small quantity of the gas in the air is fatal 
to vegetable life, so that trees and shrubs in the vicinity 



THE ATMOSPHERE 15 

of smelters and chemical works, especially on the side toward 
which the prevalent wind carries the fumes, are killed. 

There is an interesting form of oxygen known as ozone. 
It was noticed many years ago that a peculiar smell ac- 
companied a thunderstorm, and this as well as the lightning 
was ascribed to evil spirits. As early as 1785 Van Marum 
noticed a peculiar odor in the vicinity of an electrical 
machine, and recognized that it was the same as that ac- 
companying lightning discharges. It was not till 1840, 
however, that Schonbein, a Swiss chemist, discovered ozone, 
and showed that electricity changes oxygen to ozone. 

In addition to the production of ozone by electrical dis- 
charges, it is formed in many other ways, as by the slow 
oxidation of phosphorus, by the partial combustion of ether, 
and by the action of sulfuric acid on potassium permanganate 
or on barium dioxid. Ozone slowly changes back to oxygen 
at 100° C. and rapidly at 300° C. It has been shown that one 
volume of ozone can be smelled if present in 2\ million 
volumes of air. When a known volume of ozone is changed 
back to oxygen, there is an increase in volume. This is due 
to the fact that a molecule of ozone contains three atoms, 

thus ( 97"/ ) j an( i a molecule of oxygen, two atoms (0 = 0). 

Ozone is a very powerful oxidizing agent and on this account 
has been considered extremely useful in the purification of 
the air and the oxidation of its impurities. 

It was for a long time supposed that the test with " ozone 
paper" was a positive proof that ozone existed in the air, 
but as other substances, such as some of the oxids of nitro- 
gen, color ozone paper in a similar way, there is still some 
doubt as to whether it exists in appreciable quantities in the 
atmosphere. 

Hydrogen peroxid (H 2 2 ) is a powerful oxidizing agent 
which is present in the air, and in rain and snow water. It 



16 SANITARY AND APPLIED CHEMISTRY 

is probable that some of the effects ascribed to ozone are 
really due to hydrogen peroxid, on account of its similar 
oxidizing action. The use of this substance as a disinfectant 
is well known. 

Experiment 12. To make " ozone paper/' mix about 5 g. 
of starch with 20 cc. of cold distilled water. Pour this into 
a beaker containing 100 cc. of boiling water, in which has 
been dissolved a gram of potassium iodid. Heat the mix- 
ture for a moment. Soak strips of white filter paper in this 
solution and allow them to dry in pure air. 

Experiment 13. To make ozone, turn a static electrical 
machine and test the air in the vicinity by means of moist 
ozone paper. The paper should turn blue. 

Experiment 14. Heat a large glass rod in a Bunsen 
burner. Pour a few drops of ether into a medium-sized 
beaker and move the rod around in the vapor of ether. Test 
this vapor for ozone, which with other products is probably 
present. 

Experiment 15. Cut some phosphorus in thin slices under 
water, and place them in a cylinder with a little warm water 
in the bottom, but not enough to cover the phosphorus. 
Suspend some pieces of moist ozone paper in the jar and 
place a cover over it. After a time the paper will turn blue, 
showing the presence of ozone. 

SUBSTANCES IN SUSPENSION IN THE AIR 

Although the air is apparently clear and transparent, yet 
we have only to admit a ray of sunlight into a room to see 
the dust which is in the air. "Minute particles of any- 
thing and everything that exists upon the earth are liable 



THE ATMOSPHERE 17 

to be mingled in the air that rests on it. These suspended 
matters are furnished by animal, vegetable, and mineral 
kingdoms. nl TVe get, in the animal kingdom, the debris of 
little creatures suspended in the atmosphere — eggs and 
other substances. From the vegetable kingdom we get 
spores of fungi, bacteria, pollen of plants, seeds of all kinds, 
particles of straw, etc. From the soil, the dust of inorganic 
composition, such as sand, iron oxid, lime, mud from vol- 
canoes, particles of carbon, sulfur, and in the vicinity of the 
ocean, sodium chlorid and other minerals carried long dis- 
tances by the "wind. 

The air of sick rooms, hospitals, and prisons has been 
carefully examined, and a microscopic study has been made 
of the dust collected. It has been found to contain a variety 
of organic matter. The first method of examination is by 
passing a known quantity of air through a tube closely 
packed with sterilized cotton, and then Trashing the cotton 
and examining the wash water. By this means we can 
arrive at the number of spores per liter of air. A known 
volume of air may be drawn through sand or sugar and steril- 
ized liquid gelatine added to this, and finally the number of 
colonies in the gelatine may be counted. A more convenient 
method, however, is what is known as the plating method, 
in which we pour into a series of shallow glass vessels a 
nutrient medium which becomes solid on cooling. To this 
the dust particles readily adhere. This gives a moist, sticky 
surface, which can be easily protected by tightly fitting 
covers. TThen we desire to examine the air in any locality, 
one of these vessels is opened and exposed to the air for 
a specified time, say 25 min. In this way it is possible 
to compare the air in different localities. By counting colo- 
nies, each one of which presumably consists of the off- 
spring of a single germ, the following numbers of bacteria 
1 Fox, "Water, Air, and Food," p. 264. 



18 SANITARY AND APPLIED CHEMISTRY 

were found under different conditions in New York 
City: — 

Central Park, dust blowing 49 

Union Square 214 

In a private house 34 

Dry goods store 199 

Broadway and 35th St 941 

When the street was being cleaned . . . . 5810 

In a house called clean 180 

In a filthy house 900 

In a dirty schoolroom with natural ventilation . . 2000 

Average in hospitals and dispensatories . . . 127 

There are in fact more living microorganisms in the air 
than the above results would indicate, for many germs do 
not find in the nutrient medium conditions favorable to 
development. It is understood that these organisms are 
of widely different character and they are generally either 
molds, yeasts, or bacteria. It is estimated that in the 
open country in a cubic inch of air there may be 2000 dust 
particles, 3,000,000 in the air of city streets, and 30,000,000 
in that of inhabited rooms. 1 While microorganisms are 
very abundant in the air of towns, there are hardly any 
at great heights and at sea. Pasteur exposed a large num- 
ber of flasks of broth at an altitude of 6000 feet, and ob- 
tained a growth in but one. Tyndall exposed twenty-seven 
flasks at 8000 feet and got no growth whatever. Dr. Fisher 
has shown that on the ocean 120 miles from land the air is 
usually free from organisms and that at a lesser distance 
— 90 miles for example — it contains but few. 2 

Dust, however, is of great importance on account of its in- 
fluence upon the precipitation of rain, upon clouds and fog. 

There are certain diseases, such as consumption, diphtheria, 

1 Nature, Vol. 31, p. 265 ; Vol 41, p. 394. 

2 Harrington, ''Practical Hygiene," p. 233. 



THE ATMOSPHERE 19 

smallpox, yellow fever, Asiatic cholera, scarlatina, measles, 
etc., which are called infectious, and which are often propa- 
gated by bacteria in the air. Much attention has been paid 
to the propagation of consumption, and the Bacillus tubercu- 
losis has been quite thoroughly studied. It is stated that in 
Europe about a million persons die annually from consump- 
tion, and one tenth of all the people of the civilized world 
fall victims to this disease. Dr. Francine (J". Am. Med. Ass'n., 
1905) says that 110,000 persons die every year in America 
from consumption. This is a disease in which the germs 
from the dry sputa are carried in the air, lodged in the air 
passages, and if they find the system in the right con- 
dition, they commence to grow and carry on their deadly 
work. 

A few years ago there was a great outcry against arsenic 
in wall paper, and it was said that the dust of many rooms, 
in which the walls were hung with ordinary paper, was laden 
with arsenic. An excellent article on this subject appeared 
in the Eeport of the Massachusetts Board of Health for 1883. 
The agitation of those times no doubt caused the manufac- 
turers to substitute other coloring matters in the place of 
arsenical, so that at the present time, it is very unusual 
to find a wall paper that contains arsenic. 

Experiment 16. To test for arsenic in paper or in fabrics, 
cut the paper or green cloth into shreds, and boil this in a 
test tube, half full of water. Add to this about 10% of 
strong hydrochloric acid and a very small, bright piece of 
copper foil. Boil the liquid for at least five minutes and 
notice if there is any dark coloration on the copper. When 
no coloration appears, arsenic is absent. If there is a colora- 
tion or deposit, remove the piece of copper carefully and 
wash thoroughly. Dry it on a piece of filter paper over a 
lamp and then place it in a matrass, and heat cautiously. 



20 SANITARY AND APPLIED CHEMISTRY 

If arsenic is present, there will be a sublimate of crystals of 
arsenious oxid (As 2 3 ) on the inside of the tube. Examine 
these crystals with a lens and notice also if they reflect light 
or show triangular faces. 

INJURIOUS TRADES 

There are many trades in which the health of the work- 
men suffers from dust or injurious gases. Dr. Hirt has 
studied the effect of various trades on the health of the 
workmen in Germany. He made a particular study of con- 
sumption among the workmen, and gives the following as 
a list of the most injurious trades : flint cutting, needle 
and file making, lithographing, binding, brush making, 
stone cutting, grindstone cutting, type founding, cigar mak- 
ing, molding, glass working, dyeing, and weaving. The 
sharp mineral dust is by far the most injurious. The worst 
vegetable dust is cotton fiber, and this produces great mor- 
tality, especially among women. The mortality is probably 
increased on account of the high temperature and lack of 
ventilation in the manufactories where they are obliged 
to work. 

GROUND AIR 

Air is contained in the ground sometimes to a depth of 
20 feet. It is forced into the ground both by its weight and 
by the pressure of strong winds. Pettenkofer found in 
1870 that the air contained in the ground is not as pure 
as ordinary air. A comparison of dry ground air with ordi- 
nary dry air is given by Price. 1 

Average Composition of Atmospheric Air in 100 Volumes 

Nitrogen 79.00% 

Oxygen . 20.96% 

Carbon dioxid .04 % 

1 " Handbook of Sanitation," p. 3. 



THE ATMOSPHERE 21 

Average Composition of Ground Air 

Nitrogen 79.00% 

Oxygen 10.35% 

Carbon dioxid . . . . . . .9.74% 

The excess of carbon dioxid is due to decay of organic 
matter that has taken place in the soil, and the decrease in 
oxygen is due to the fact that it has been used up by the 
bacteria and in various processes of oxidation. This air also 
contains a large number of bacteria, and other organic forms 
of life. When we remember that a cubic centimeter of earth 
contains from 200,000 to 1,000,000 bacteria, the opportuni- 
ties for contamination of the ground air are apparent. The 
air of virgin soil is usually more free from organic impurities 
than the air from the ground of thickly populated districts, 
and the difference can be readily understood when we consider 
the material which is liable to collect in or filter through the 
soil of a city. Fatal results have sometimes followed the 
breathing of air poisoned by the decaying of organic matter. 
Sir Henry Thompson states that gravediggers have died 
while digging in the region of vaults and cemeteries. 1 If 
houses are built upon the so-called " made " land that has 
been filled in with all sorts of refuse from the city and from 
manufactories, the air that comes into the rooms is liable 
to be contaminated and to be deficient in oxygen. On 
account of the vitiation of air by decaying organic matter, 
in large cities, cremation has been quite extensively advo- 
cated and is no doubt an excellent method for the disposal 
of garbage and dead bodies. 

OFFENSIVE GASES 

In the ordinary apartment there is little danger of injury 
from poisonous gases. In the centers of trade the gases 

1 " Cremation," R. E. Williams, p. 44. 



22 SANITARY AND APPLIED CHEMISTRY 

from some manufactories would be offensive, if they were 
taken into the lungs, but they are rapidly diffused through 
the atmosphere. Even sewer gas, which is usually con- 
sidered so dangerous, has been shown frequently to contain 
a less number of microorganisms than the outside air. This 
gas is, of course, disagreeable, often lacking in oxygen, and 
should by no means be allowed to escape into a dwelling. 



CHAPTER II 
FUELS 

In the production of heat for ordinary purposes, such 
fuels as wood, charcoal, peat, lignite, bituminous coal, cannel 
coal, semianthracite, anthracite, coal gas, and natural gas 
are used. Wood spirit, denaturized alcohol, common alcohol, 
gasoline, and kerosene find a limited use; and electricity 
may be used for heating under special conditions. 

The combustible elements in these fuels are carbon and 
hydrogen, the former burning with scarcely any visible flame, 
and the latter also burning with a colorless flame. The 
calorific power of fuels, that is, the quantity of heat evolved 
by burning one gram in oxygen, differs greatly. 

The unit, in terms of which quantities of heat are meas- 
ured, is the calorie. A calorie is the quantity of heat re- 
quired to raise the temperature of one gram of water one 
degree centigrade. Since this quantity varies with the tem- 
perature of the water, it is usual to specify that the water 
shall be at 15° C. and be raised to 16° C. 

The Calorific Power of some combustibles is as follows : 1 — 



Hydrogen, to liquid water 



Marsh Gas (CH 4 ). . 
Olefiant Gas (C 2 H 4 ) . 

Sulfur 

Wood Charcoal, to C0 2 



34,462 Carbon, to CO . . . . 2,473 



13,063 Carbon monoxid (CO) . 5,607 

11,858 Dry Wood, about . . . 3,654 

2,221 Coal, about 7,500 

8,080 

As many combustibles contain some oxygen in addition 
to the carbon and hydrogen, in order to find the actual 

1 Favre and Silbermann. 
23 



24 SANITARY AND APPLIED CHEMISTRY 

amount of heat developed, we estimate what would be pro- 
duced from the combustion of the carbon, and of so much 
hydrogen as is in excess of that necessary to form water 
with the oxygen present in the fuel. In estimating the 
available heat produced, we must deduct from the total 
calorific power the amount of heat necessary to convert 
into steam all the water formed by the combination of 
the hydrogen, and all the water originally present in the 
fuel. 

When the carbon is burned, the sole product of the com- 
bustion is carbon dioxid, thus, C + 2 = C0 2 ; but if the 
combustion is incomplete from lack of sufficient air, the 
combustion would be represented also by the equation, 
2 C + 2 = 2 CO, in which the poisonous gas, carbon mo- 
noxid, is formed at the same time as the carbon dioxid. It 
will also be seen from the above table that much less heat 
results from the burning to carbon monoxid than when the 
carbon burns completely to carbon dioxid. Smoke consists 
largely of unburned carbon, which might have been burned 
completely to carbon dioxid if the conditions for combus- 
tion had been better. 

In the burning of hydrogen, nothing but water, in the form 
of steam, is produced, thus, 2 H 2 + 2 = 2 H 2 0. In addition 
to the above products there are some others that are inci- 
dental, and due to impurities in the combustibles. 

The original basis of the ordinary fuels is cellulose 
(C 6 H 10 O 5 ) n , which is found in a very pure form in clean 
cotton and in pure filter paper. It is believed by geolo- 
gists that not only peat, but also the different kinds of coal, 
came originally from vegetable material. In the case of peat 
the amount of oxygen and hydrogen have not been so com- 
pletely eliminated by the combined action of heat and 
pressure in the earth, as in the case of the soft coals and 
anthracite. 



FUELS 25 



WOOD AS FUEL 

If a fuel is porous, like wood, so that the air can penetrate 
into the interior, it will be readily ignited and burn quite 
freely. The ordinary practice of piling the wood loosely to 
build a fire is, of course, in accordance with this principle. 
If the fuel contains considerable hydrogen, especially when 
united with oxygen, as is the case with wood, it is free 
burning. When but little luminous gas can be formed, as 
in the burning of charcoal, coke, or anthracite, the heat is 
more intense and concentrated at a point near the burning 
material. Other fuels, such as wood, soft coal, petroleum, 
etc., burn with a long, smoky flame, and the heat will be 
distributed over a larger flue surface. 

The experience of foresters, both in this country and in 
Europe, has shown that to be fit for fuel and economical for 
use, the softer woods must grow from twenty to thirty years 
and the harder woods from fifty to one hundred and twenty 
years. In many parts of Europe the government requires 
that the forests be renewed as often 1 as they are cut, and 
only in this way is it possible to keep the supply of fuel 
and timber intact. The preservation of forests also tends 
to keep the moisture in the soil, so that the streams shall 
not dry up in summer and there will not be the liability to 
sudden floods that there is in regions from which the tim- 
ber has been cut. 

There is more water in wood that is cut in the spring than 
if it is cut in January, and there is more in the young twigs 
and stems than in older wood. Different varieties of freshly 
cut wood contain the following per cent of water : — 

Willow 26.0% Aspen 43.7% 

Sycamore 27.0% Elm 44.5% 

Birch 30.8% Fir ....... . 45.2% 

Oak 34.7% Larch 48.6% 

Pine 39.7% White Poplar .... 50.6% 

Beech 39.7% 



26 SANITARY AND APPLIED CHEMISTRY 

One and a half to two years after being cut wood gets as 
dry as it can by simple exposure to the air, and it is called 
"seasoned" or " air dried," but it still contains from 20% 
to 25 % of moisture. 

Wood several years old, kept in a warm room, may still 
retain 17 % of moisture. Wood may be kiln-dried, and in 
this process will lose from 16% to 20% of moisture. If 
the air is expelled from wood, it is sensibly heavier than 
water, and the specific gravity is from 1.30 to 1.50. On ac- 
count of being heavier than water, "water-soaked" wood, or 
that in which all the air has been replaced by water, will of 
course sink to the bottom of a stream. 

The amount of moisture in wood is of great importance, 
because of the large amount of heat that is used up in its 
evaporation when burning; and so it goes without saying 
that dry wood is more economical than green wood. Eesin- 
ous woods, such as fir, spruce, and pine, have an increased 
heating value on account of the pitch and resinous gums 
which they contain. 

The amount of ash in wood differs greatly as it is made 
from old or young wood and from the whole wood or the 
bark. Willow wood contains 2% of ash; oak, 1.65% ; beech, 
1.06 % ; Scotch fir, 1.04 % ; birch, 0.85%. This ash consists 
essentially of sodium and potassium carbonates, calcium 
and magnesium carbonates, with some phosphates, sulfates, 
and silica (see Soap, p. 96). 

CHARCOAL 

When wood is heated in a limited supply of air, a kind of 
distillation takes place, and the residue that is left is called 
charcoal. The ordinary method of charcoal making has 
been to pile the wood and cover with turf or soil, and then 
apply a flame to the center of the pile and allow a little air 



FUELS 27 

to enter the bottom so that the combustion shall go on slowly. 
This process requires several weeks, and no attempt is made 
to utilize the smoke and gas given off. 

Charring in kilns has more recently been resorted to, and 
here the products of combustion are utilized. The wood is 
placed in a brick kiln, which is heated by the combustible 
gases given off from other furnaces of the same battery. 
The smoke and other products of combustion are drawn out 
of the kiln by fans, through a series of condensers, where the 
wood alcohol, tar, and crude acetic acid are deposited, and 
afterward purified for the market. About 27% of charcoal 
is the yield, by this process, while only 20 % is produced by 
the charcoal pit process. 

PEAT 

This fuel is very slowly formed, especially in shallow 
pools, by the decomposition of vegetable matter. The peas- 
ants in Great Britain, Northern Germany, Holland, and 
some other countries cut the peat or " turf," as it is some- 
times called, into cubical blocks and pile it up on platforms 
to dry. As it often contains as much as 45 °} of water, it is 
important that the drying should be thoroughly done, or in 
burning but little heat will be obtained. It is, of course, a 
cheap fuel and burns with a smoky flame. 

A peat bog is composed of the various mosses and sedges 
that grow so readily in damp ground and die at the end of 
the season, to be succeeded by similar vegetation the next 
season. Sometimes trunks of trees are found in it and even 
animal remains. Peat has about the following composition : 
water, 16.4 ; fixed carbon, 41 % . 

It is estimated that there are in Great Britain 6,000,000 
acres of peat swamps, and that each acre would yield 1000 
tons of peat charcoal. In Ireland one seventh of the whole 
island, or 2,830,000 acres, is peat bog. The value of peat 



28 SANITARY AXD APPLIED CHEMISTRY 

depends on its dryness, density, and firmness. Peat leaves 
from 8 % to 12 % of ash. 

COAL 

Lignite or brown coal is intermediate between peat and 
ordinary soft coal in composition, and is of more recent for- 
mation than the latter. Although it burns freely, it contains 
from 15 % to 20 % of moisture, and leaves quite a large 
amount of ash. 

Cannel coal is a peculiar variety of coal, having a con- 
choidal fracture like broken glass, and only a slight luster. 
The name comes from the Scotch pronunciation of the 
word " candle," and refers to the fact that splinters of this 
coal will burn like a candle. Cannel coal is especially valu- 
able for making illuminating gas, as it yields a large quan- 
tity per ton. 

Bituminous coal is very widely distributed in most coun- 
tries of the world. Some of these coals burn with a smoky 
flame, and " cake," or form a coke which is hard and seems 
to fuse together, while others are " non-caking," and burn 
freely, with little smoke, to an ash. The latter are well 
adapted for domestic use. 

In the use of an oven that is heated with a fire on the 
outside, this is a cheap and satisfactory fuel, except for the 
abundance of smoke which it gives off. 

Semibituminous coals are found in several localities, but 
particularly from Pennsylvania across the southern bound- 
ary of Virginia into Tennessee. The volatile matter ranges 
from 12% to 25%, and this combustible portion is quite 
uniform in composition. 

The semianthracite coals, like the Eureka and Ouita of 
Arkansas, burn freely, with but little flame, and show a ten- 
dency to decrepitate and fall through the grate. 

Anthracite coal occurs only in a few localities, but often 



FUELS 



29 



in very thick veins. It has a high luster, and a specific 
gravity of about 1.75. It burns with little flame and 
smoke, and is admirably adapted for domestic use, as the 
heat is concentrated and intense directly over the fire 
rather than distributed through a long flue as when soft coal 
burns. When a naked fire is used for baking, as in a large 
cracker bakery, anthracite or coke is a very satisfactory fuel. 
Coke, the material left in the retort after gas has been 
made from soft coal ( see p. 54 ), is quite a bulky fuel, 
and leaves considerable ash. It is also made in " beehive " 
coke ovens, and the distillation products are allowed to 
escape. 

Analysis of Various Coals 





Water 


Volatile and 

Combustible 

Matters 


Fixed 
Carbon 


Ash 


Lignite 

Semibituminous, Pa. 1 
Bituminous, Pa. 1 . . . 

Cannel 

Canon City, Colo. . . . 
Semianthracite, Ark. . . 
Anthracite l 


18.00 
0.81 
1.97 

undet. 
6.47 
1.11 
3.09 


20.90 
21.10 
38.60 
37.20 
38.82 
12.73 
4.28 


50.90 
74.08 
64.15 
61.60 
49.10 
77.62 
83.81 


10.20 
3.36 
4.10 
1.20 
5.61 
8.56 
8.18 



The greater the amount of moisture the less valuable the 
fuel, as in the case of wood mentioned above. The " vola- 
tile and combustible " matter- referred to in the table, is that 
which goes off when the coal is heated in a closed vessel. It 
is this which gives the smoky flame to bituminous coal. 
Fixed carbon is the coke, which finally burns with little 
flame and leaves a residue of ash. It will be noticed that 
there is a regular decrease in volatile matter, from the bitu- 
minous coal to the anthracite, and a corresponding increase 

in fixed carbon. 

1 Trans. A. I. M. E. 



30 SANITARY AND APPLIED CHEMISTRY 

Experiment 17. Heat about 2 g. of pulverized bitumi- 
nous coal in a platinum or porcelain crucible closely covered, 
as long as any smoke is given off. When the cover is re- 
moved, the mass of coke will be found in the crucible. This, 
less the ash which would remain on complete combustion, 
constitutes the " fixed carbon " referred to above. 

In many localities where there is no local supply of coal, 
there is a direct relation between the retail cost of different 
kinds of coal and the amount of fixed carbon which they 
contain, — the greater the per cent of fixed carbon the 
higher the price. 

Experiment 18. Compare the retail price of different 
kinds of coal, as anthracite, semianthracite, bituminous, 
etc., and the composition as given on page 29. 

Natural and artificial gas are both important fuels, even 
for domestic use. Natural gas has been in use on a small 
scale for a number of years, but it was not until about 1880 
that it became of commercial importance in the United 
States. It is now obtained in quite large quantities in 
Pennsylvania, New York, West Virginia, Ohio, Indiana, 
Kentucky, Texas, and Kansas. The method of boring the 
well is to use what is called a churn drill, which pulverizes 
the rock, and the borings may then be washed out with a 
stream of water. 

The hole, which is from 4 to 6 in. in diameter, is usually 
cased with iron pipe as the drilling progresses, but the cas- 
ing is smaller nearer the bottom. The depth is usually from 
300 to 1600 feet. The gas occurs in what is called a " gas 
sand," which is often quite thick. The pressure of the gas 
is frequently from 300 to 400 lb. per square inch, so that 
it is with great difficulty held in check. The gas is often 
conveyed in pipes for hundreds of miles, and finally, by 
regulators, the pressure is reduced for domestic consumption 



FUELS 31 

so that it shall be burned at from 4 to 8 inches of water 
pressure. 

A cheap fuel gas can be made in some sections at a low 
price, and will, it is hoped, supersede the use of coal for 
cooking and heating in large towns and cities where nat- 
ural gas cannot be obtained. The advantages of burning 
gas over any other fuel are obvious, for it is immediately 
available to warm a house or cook a meal, and there is no 
waste of fuel, when the occasion for its use is past. There 
is no dust, ashes, or smoke, and the products of combus- 
tion can be carried out of the room by a very small pipe. 
These products should, however, always be removed, for if 
allowed to accumulate, the carbon dioxid and other gases 
make the air of the room decidedly impure. The gas stove 
does not heat the room in summer as does a coal stove, and 
it is a perfectly safe fuel, which is more than can be said of 
gasoline as ordinarily used. 

The burners used in heating by gas are all made on the 
principle of the Bunsen burner. The proper amount of air is 
allowed to enter at the bottom of the tube or, in the large 
burners, through the " mixer." The burner that is put into 
a cook stove, for instance, can be made of a piece of two- 
inch gas pipe capped at one end and having three rows of 
small holes drilled in the top from one end to a point near 
the other. The " mixer " is screwed on at the end through 
which the gas is admitted. There is little danger in the 
use of natural gas if ordinary precautions are taken. There 
is, of course, a possibility that the pressure may change so 
that the gas may go out at night, but this is not often the 
case with the present methods of regulating the supply. It 
is true that there are some cases of suffocation from the 
careless use of natural gas, but it is not as poisonous as coal 
gas or "water gas" (see Lighting, p. 54). 

The composition of natural gas from different localities is 
as follows : — 



32 



SANITARY AND APPLIED CHEMISTRY 



Ohio 



Indiana 



Kansas 



Russia 



Carbon dioxid . 
Carbon monoxid 
Marsh gas . . . 
Nitrogen . . . 
Oxygen . . . 
Hydrogen . . . 
Hydrogen sulfid 
defiant gas, etc. 



.3 

.5 

92.6 

3.5 
.3 

2.3 
.2 
.03 



.25 

.45 

92.67 

3.53 
.35 

2.35 
.15 
.25 



.44 
.33 

95.28 
3.28 



.95 

92.49 
2.13 

.94 

4.11 



The preparation and properties of illuminating gas are 
discussed under Lighting, p. 53. 

Gasoline, one of the products from the distillation of 
petroleum, which is so extensively used as a fuel for cook- 
ing in some localities, is burned in stoves so constructed that 
the liquid is converted into vapor by the heat of the burner 
before it is burned, and it is also mixed with sufficient air 
so as to burn completely with a blue flame, which does not 
deposit soot on the cooking utensils. 

The chief danger in the use of gasoline is due to the fact 
that it gives off a volatile vapor, even at ordinary tempera- 
ture. The vapor of gasoline is not only extremely com- 
bustible, but when mixed with a certain proportion of air it 
is highly explosive. Gasoline stoves are usually so con- 
structed that the tank which holds the liquid is at some 
distance from the flame and it should never be filled without 
first putting out the fire. 

Kerosene is often used as a fuel for heating and cooking. 
It should be burned in stoves of special construction, and 
usually from a large flat wick. There is danger of smoking 
unless the wick is carefully trimmed. The products of com- 
bustion should always be carried away by a suitable flue, as 
they are both disagreeable and injurious. 



CHAPTER III 

HEATING AND VENTILATION 

HEATING 

These two subjects are so intimately associated that one 
cannot be considered without the other, and one system 
should be installed at the same time as the other. 

The common methods of heating are through — 

(1) Direct radiation. 

(2) Indirect radiation. 

(3) Direct-indirect radiation. 

The means of obtaining the heat are : — 

By the fireplace or open grate. 

By stoves. 

By hot-air furnaces. 

By steam with direct radiation. 

By steam with indirect radiation. 

By hot water with direct radiation. 

By hot water with indirect radiation. 

By electricity. 

Direct radiation includes the use of a fireplace or open 
grate, which, however satisfactory it is in the way of ventila- 
tion and for imparting cheerfulness to a room, is not an 
economical method of heating, because it wastes from 75 °J 
to 90 °}o of the fuel. The fireplace, where only the radiant 
heat was utilized, was the primitive method of heating dwell- 
ings when fuel was not expensive. Many devices have been 
d 33 



34 SANITARY AND APPLIED CHEMISTRY 

proposed for making the fireplace more efficient. Among 
them may be mentioned the ventilating grate, in which air 
is brought from outside and heated by passing back of 
the fire and then comes into the room through gratings 
above the fireplace. The Franklin stove, when placed partly 
in the room, was an illustration of heating by a combination 
of the radiation and convection methods. One of the chief 
reasons why people take cold so easily is that they work, eat, 
and sleep in rooms that are heated to a high temperature, 
with little moisture, and where no attention is paid to ven- 
tilation. The fireplace, which was universally used less than 
seventy-five years ago, furnished pure air, although the heat 
of the room was badly distributed. 

Under the head of direct radiation may also be included 
the heating by stoves, or by pipes or radiators carrying 
steam or hot water. When the room is heated by a stove, 
as air is necessary for the combustion of the fuel, and there- 
fore is removed from the room through the chimney, an 
equivalent amount must enter the rooms through the cracks 
around the doors and windows. This affords some venti- 
lation, but not enough for rooms in which a number 
of persons are assembled. Direct radiation systems are 
cheaper in construction and, with the exception of the open 
grate or fireplace, do not use as much fuel as indirect 
systems. 

When rooms are heated by a stove, there is no reason why 
air cannot be brought in from the outside beneath the stove, 
and pass over it to become heated, and then into the room. 
By this means fresh air will find its way into a room, and 
there is little difficulty in removing air from a room, espe- 
cially if it is warm or under a little pressure. 

In the use of the stove for heating, it should be large 
enough to thoroughly heat the room, even in the coldest 
weather, without running it at its fullest heating capacity. 



HEATING AND VENTILATION 35 

It is not economy to heat a room with a small radiating 
surface. The air of the room that is in contact with this 
surface becomes overheated. Stoves heat a room largely 
by convection, that is, by heating the air that is directly in 
contact with the stove, and when this becomes heated, it 
rises and gives place to colder air. 

The openings at the bottom of a stove or furnace should 
be so arranged as to completely shut out the air if necessary, 
and thus control the fire. This is much safer than the prac- 
tice of shutting the damper in the pipe as this will often 
drive the products of the combustion into the room; this 
might occur during the night, especially if the wind dies 
down, and the suffocating carbon dioxid and sulfur dioxid, 
as well as the more dangerous carbon monoxid, would be 
driven into the room. When sufficient air for complete 
combustion is not admitted below the fire, more carbon 
monoxid will result, and the full heating value of the fuel 
will not be obtained. 

Indirect radiation may be secured in the simplest way by 
the use of the ordinary hot-air furnace. Here air is brought 
from the outside and passes over the heated surface of the 
iron, and is then admitted to the room. If, in addition to 
this, open grates or fireplaces are used, the heating is nearly 
uniform and the ventilation is satisfactory. 

If a building is heated by a furnace, great care should be 
taken that the air that comes into the room is from out of 
doors and not from the cellar. The danger of ground air 
has been spoken of (p. 20), and this danger is still greater 
if it is contaminated with the gases that arise from decayed 
vegetables in the cellar. The amount of air coming into the 
furnace can be regulated if it is brought in from outside, 
and an excess, or more of the cold air than is thoroughly 
heated, can be avoided. If there is not enough air, the flues of 
the furnace are liable to become overheated, and the furnace 



36 SANITARY AND APPLIED CHEMISTRY 

will thus be damaged, and the air that does come in under 
these conditions will also be liable to contain carbon monoxid 
(see p. 13) and on this account be poisonous. The open- 
ing for the admission of fresh air should be so arranged 
that the winds will not seriously affect the amount of air 
admitted. 

It is a common practice to take the air from the living 
rooms and the hall of the dwelling and return it over the 
furnace, thus using the same air over and over again. While 
this is no doubt economical, as far as expense of fuel is con- 
cerned, a part of the air at least should be taken from out of 
doors, and air should be reheated only in the coldest weather, 
and for warming the house in the morning. 

There should always be some arrangement for adding 
moisture to air that is heated, as the capacity of heated air 
for taking up moisture is greatly increased ; and if moisture 
is not supplied, unpleasant sensations from the apparent 
dryness of the air are produced and there is greater liability 
to take cold. Pans of water are placed in the hot-air 
chamber of a furnace to allow the moisture to evaporate 
and mix with the air which enters the room. 

In the use of steam with indirect radiation, it is conven- 
ient to have steam coils in the lower part of the building 
so situated that fresh air can pass over them, and then 
through suitable flues into the rooms above. Here again 
some provision can be made to keep the incoming air moist, 
by placing pans of water upon the steam coils. 

Steam is generally used under a pressure below twenty 
pounds per square inch, so the temperature is not very much 
above 100° C. (212° F.), or " exhaust " steam from an engine 
may be used. In some systems high pressure-steam is em- 
ployed, and in this case the temperature of the radiators 
is considerably above 100° C. If direct radiation is used, 
one disadvantage of this method of heating is that the air 



HEATING AND VENTILATION 37 

in the room is dry. In order to obtain heat from the steam, 
it must be condensed in the radiator, so there must be an 
opportunity for the water to run back freely to the boiler 
or to a steam trap. 

Water is used for heating on account of its great capacity 
for retaining heat. The hot water can be carried in pipes 
to some distance from the boiler, give up its heat, and then 
be returned by another series of pipes to the boiler. The 
water in the system may be under pressure, but it is usually 
carried in an open system, with a small tank at the top of 
the building, which is filled occasionally to supply the waste 
of evaporation or leakage ; and vents must be provided to 
allow the air that is dissolved in the water to escape. Under 
these conditions the hot water from the boiler in the cellar 
flows upward through the pipes and radiators and warms 
the building, and the heavier cold water runs back to the 
boiler and enters at the bottom through another set of pipes, 
and the heat keeps the water circulating. It should be 
noted that the difference in weight between the column 
of hot water and that of cold water is what keeps up the 
circulation in the system. 

The hot-water system has this advantage over steam that 
as soon as the water is warm enough to circulate it begins 
to warm the room, and the heat is retained for a long time 
after the fire has been allowed to die down. In the case of 
steam there is no heat from the radiator till the water in the 
boiler is above the boiling point. With the use of hot water 
the temperature of the radiator is never above 100° C. 
and usually much below this, and with a suitable surface 
for evaporating water in the rooms the air will be agreeable. 
As the temperature of the radiating surface is lower than in 
the case of steam, the heating surface must be much larger, 
and so it is more expensive to install a hot-water system. 
This is no doubt the chief reason why it is not more 



38 SANITARY AND APPLIED CHEMISTRY 

generally used, and added to this is the greater liability to 
leaks, and the danger from freezing if not handled with care. 

In the direct-indirect method of heating, air is brought 
from the outside behind or below a steam or hot-water 
radiator standing in the room, and is heated in its passage 
over the radiator. This is also theoretically very satisfac- 
tory, as good ventilation is secured, though it is not often 
attempted on a large scale. 

At the present cost of electricity, it is not extensively 
used for heating, except in the case of street cars and 
small offices. With the increased use of water power to 
produce electricity, the use of this heating agent will no 
doubt soon be much more common. The use of electrical 
cooking devices is already quite large. They are especially 
adapted to small apartments, or rooms where there is extra 
danger from fire. 

VENTILATION 

But little attention is paid to ventilation by people in 
general, because they do not appreciate the injury to the 
body as it is so gradual. The evil effect of bad air can be 
readily shown by the study of the health of those who are 
confined in close, badly ventilated barracks or tenements, 
or of workmen in crowded factories. Even domestic ani- 
mals thrive much better in light, clean, well-ventilated 
stables. Consumption in some form is the result of living 
in close, badly ventilated rooms. A practical demonstration 
of the fact that pure air is inimical to the growth of the 
bacilli that cause consumption is shown in the recent methods 
of treating this disease by requiring patients to live out of 
doors throughout the entire year, and in the establishment 
of sanatoria in elevated regions, where an abundance of fresh 
air is the most important part of the treatment. 

Many public buildings have no provision for ventilation 



HEATING AND VENTILATION 39 

during that part of the year when they must be heated, and 
this is the case even with those buildings that are intended 
to accommodate large audiences. There is a great want of 
appreciation of the necessity for ventilation, so that house 
renters never think of making any inquiry as to whether 
any facilities for ventilation exist or not. In many schools 
and assembly rooms there is no provision for ventilation 
except by opening windows and subjecting the audience to 
a dangerous draft. One reason for this, no doubt, is that 
we do not notice that air is impure until it is extremely 
impure. We suffer great discomfort, especially from high 
temperature, and then think that we need fresh air. 

It is estimated that the daily respiration of each indi- 
vidual is 346 cu. ft., 1 and the amount of carbon dioxid 
given off from the lungs in the same time is 16.25 cu. ft. 
It might seem that carbon dioxid that is produced by the 
combustion of oil and of gas and in the process of respira- 
tion, since it is heavier than the air, would sink to the 
bottom of the room, and remain there ; but the fact is that 
an analysis of the air will show that on account of the dif- 
fusion of gases, the gas in question will be nearly uniformly 
distributed throughout the room. To such an extent is this 
the case that we expect to find greater discomfort in the 
gallery of a crowded hall than on the first floor, since the 
expired air being warmer tends to rise, notwithstanding its 
greater content of carbon dioxid gas. 

The air of overcrowded, poorly ventilated rooms, as a 
result of life processes, is altered as follows : 2 — 

"There is a slight diminution in the amount of oxygen; 
there is an increase in the amount of carbon dioxid along 
with the organic pollution, resulting from the decomposition 
of perspiration and epithelium on the surface of the body, 

1 J. S. Billings, " Ventilation and Heating," p. 88. 
2 Ibid., p. 99. 



40 SANITARY AND APPLIED CHEMISTRY 

and from gastric and intestinal digestion and decomposi- 
tion; and there is a slight elevation of temperature and 
addition of moisture. In the impure air there are more 
solid particles often organic upon which may be deposited 
either innocent or disease-producing bacteria, for the most 
part the former." 

A prominent author/ in speaking of this " crowd poison- 
ing/' as it may be named, calls attention to the fact that it 
induces a general lowering of the vital processes, impair- 
ment of nutrition, and loss of muscular strength ; the blood 
becomes laden with effete matters from diminished aera- 
tion; a craving for alcoholic stimulants follows on the 
nervous depression; and the subjects of this poisoning fall 
easy victims to disease. The prevalence of " consumption " 
among those workmen whose time is passed so largely in 
badly ventilated and crowded shops, which was formerly 
charged to the use of " rebreathed " air, is now believed to 
be only remotely chargeable to these conditions; for they 
produce lowered vitality and less resistance to infection by 
spores of disease, which may be inhaled with the dust, 
either in the workrooms or elsewhere. 

Of the impurities mentioned, the carbon dioxid, which in 
moderate quantities is not poisonous, is the most readily 
determined as an index of the impurity of the air, so special 
attention is given to this substance (see p. 11). 

Another source of contamination in a living room, which 
should not be neglected when the room is artificially lighted, 
is the products from the combustion of illuminating gas, oil, 
or candles. This not only decreases the per cent of oxygen 
and increases the per cent of carbon dioxid in the air, but 
it introduces other gases, such as sulfur dioxid and ammo- 
nium compounds. Ordinary burners use from 3 to 6 cu. ft. 
of gas per hour, and so in a large room there would be 

1 Willougkby, " Hygiene for Students," p. 166. 



HEATING AND VENTILATION 41 

required from 1500 to 5000 en. ft. of air per hour to properly 
dilute the products of combustion. 

According to Parkes, 1 the amount of fresh air to be sup- 
plied in health during repose ought to be : — 

For adult males, 3600 cu. ft. per hour for each person. 
For adult females, 3000 cu. ft. per hour for each person. 
For children, 2000 cu. ft. per hour for each person. 

The following may be considered as a conservative esti- 
mate of the amount of air required in buildings of ordinary 
construction: 2 — 

Cubic Feet of Air per Hour 



Hospitals .... 
Legislative assembly halls . 
Barracks, bedrooms, and works! 
Schools and churches . 
Theaters and audience halls 
Office rooms ... 
Water closets and bath rooms 
Dining rooms 



ops 



3600 per bed. 
3600 per seat. 
3000 per person. 
2400 per person. 
2000 per seat. 
1800 per person. 
2400 each. 
1800 per person. 



Those who are taking moderate exercise need one half 
more air, and during violent exercise three times as much 
air as when at rest. 

These amounts are much larger than those given by 
Morrin, the French writer, but in view of the contami- 
nation of indoor air from various sources, they do not seem 
to be too large. In the Boston Theater 50 cu. ft. per minute 
per capita is furnished. Pettenkofer says the amount 
of air should be from 23 to 28 cu. ft. per minute. Dr. 
Billings, 3 an authority on this subject, says that for audience 
halls 30 cu. ft. of air is necessary, and in legislative build- 
ings the apparatus should be such that at least 45 cu. ft. 

1 " Text Book of Human Physiology." 

2 J. S. Billings, "Ventilation and Heating," p. 129. 

3 Loc. cit., p. 128. 



42 SANITAKY AND APPLIED CHEMISTRY 

of air per person per minute can be furnished, with a possi- 
bility of increasing to 60 cu. ft. At the Vienna Opera 
House, which is considered one of the best-ventilated build- 
ings in the world, 15 cu. ft. of air per minute per capita is 
supplied. 

In order to have good ventilation, the fresh air introduced 
into the room must be ample in volume ; it must be free from 
contamination with dust and germs. It must be warmed in 
cold weather, and, if possible, cooled in warm weather, and 
it must be introduced so as not to cause a draft. There 
should be a sufficient quantity of air, so that the amount of 
carbon dioxid in the air at any time shal] not be above six 
parts per ten thousand. 

The ventilation may be downward or upward, and both 
of these methods have their advocates. The disadvantage 
of upward ventilation is that the heated air of the room is 
carried off very rapidly, thus increasing largely the cost of 
heating. Greater economy of heating is secured by drawing 
out the impure air from a point near the bottom of the room. 
If drawn off at the top, the heat does not diffuse through- 
out the room, and the floor is liable to be cold. The dis- 
advantage of downward ventilation (that is, taking the 
impure air out at the bottom of the room) is that it is 
sometimes difficult to get the currents of air to move in 
this direction. The Chicago Auditorium, however, is ven- 
tilated in this way; 10,000,000 cu. ft. of air per hour is 
furnished, with a velocity of 1 ft. per second. The air is 
changed from 4^- to 5 times per hour. This result is brought 
about by the use of four blowers to force air into the room, 
and three exhaust fans to take it out. 

In general, it may be said that ventilation may be accom- 
plished by natural draft or by a forced draft. The air may 
be forced into a room, and allowed to find its way out by 
flues, or it may be allowed to find its way into the room 



HEATING AND VENTILATION 43 

through the cracks, and be taken out by an exhaust fan. 
It is, however, greater economy of power to force air into 
a room than to draw it out by an exhaust fan. In some 
large chemical laboratories the tempered air is blown into 
the room by means of a fan, and then is carried out 
with a good draft by flues connected with hoods in the 
walls. 

As previously intimated, the most complete systems use 
both pressure blowers and exhaust fans. In some hospitals 
(and in these buildings, if anywhere, pure air is necessary) 
the air is introduced through a perforated cornice at the top 
of the room, and is then drawn out a short distance above 
the floor through flue$ which are ventilated by exhaust fans. 

Where there is no other way of securing a movement of a 
current of air, it is possible to cause the air to rise rapidly 
in flues at the side of the room, by having a gas jet or some 
source of heat in the flue. The best place for this is just 
above the openings but these flues should be much larger than 
those usually provided. Systems of this kind that work with 
more or less success, have been in use in school buildings 
for many years. In this case a fire is kept burning in the 
furnace, so as to assist in the removal of the foul air from 
the rooms and from the flues. 

When the pressure blower system is used, the air is drawn 
over the steam pipes in the winter (see p. 36), and it may 
be cooled by passing over refrigerating pipes, through which 
cold brine is circulated, in the summer. The air is fre- 
quently sprayed before it enters the room to remove dust 
or smoke, or the dry air may be filtered through cotton or 
cheese cloth, in a long flue. 

If large halls are lighted by gas, the burners should be 
placed outside the room, thus allowing the light to shine 
into the room through a glass dome. This avoids heating 
the room, and the products of combustion do not in this way 



44 SANITARY AND APPLIED CHEMISTRY 

contaminate the air. Much of the foul air of the room 
will escape also at the same time if openings are left in the 
ceiling near the place where the gas is burned. 

Open grates may be used in connection with furnace or 
radiator heat to ventilate the ordinary dwelling. If stoves 
are used in closed rooms, cold air from outside may be 
brought in below the stove, allowed to pass over it, and 
a flue may be provided near the floor for the escape of foul 
air (see p. 34). 

Various other devices have been suggested to ventilate 
an ordinary room. One of these is to bore gimlet holes in 
the walls; these are so small that the air cannot cause a 
draft, and yet they will admit a large amount of fresh 
air. An excellent plan, and one that can be easily adopted 
in any schoolroom, is to raise the lower sash and place a 
board about 5 in. wide below it, and then air will be admitted 
into the room between the two sashes and directed upward, so 
there will be no direct currents. One disadvantage of 
opening the windows at the top is that the air may pass 
to the opposite side of the room, so those persons farthest 
away from the window will feel the draft, while those near 
by will not notice it. 

The air in a well-ventilated room should be in motion, 
but this motion should not be over 3 or 4 ft. per second, 
for otherwise it becomes a " draft." The ordinary dwelling 
fortunately affords numerous openings where air from out- 
side can enter, if the air within the room is removed by a 
chimney or a heated flue. 

Experiment 19. Test for currents of air in a room by 
the use of thistle down or a candle flame. 

Experiment 20. Test the temperature at the top and 
bottom of a room, and in different localities. 



HEATING AND VENTILATION 45 

Experiment 21. Test for the moisture in both a cold and 
a warm room by the use of the hygrometer. 

Experiment 22. A " household test" for air, devised by 
Angus Smith/ is to place \ oz. of clear limewater in a 
10-1- oz. bottle containing the air to be tested for carbon 
dioxid, and if, on shaking, there is no precipitate, the air 
contains less than .06 % of this gas, and is, therefore, fairly 
pure. 

See Experiments 10 and 11 under air. 

1 Kenwood, ''Public Health Laboratory Work," p. 203. 



CHAPTER IV 

LIGHTING 

We may properly consider that there are two kinds of 
light, natural and artificial. The most common methods of 
obtaining artificial light are by — 

(1) Combustion. 

(2) Chemical action. 

(3) Phosphorescence. 

(4) Electricity. 

To obtain light, the body, if a solid, must be heated to incan- 
descence, or if a gas it must be heated till it glows. A carbon 
filament, heated to incandescence in a vacuum, as in the in- 
candescent electric light, is a familiar instance of this class 
of illumination. Again, by means of the oxyhydrogen blow- 
pipe, calcium oxid is heated to a white heat; and when 
magnesium is burned, the intense light is due to the incan- 
descent magnesium oxid. When charcoal is heated, the coal 
does not volatilize, so this is not used as a source of light, 
but of heat. When wood is heated, although the wood itself 
does not volatilize, there are certain volatile hydrocarbons 
given off, and these have the property of becoming incan- 
descent, or the carbon in them does so, and thus light is 
obtained from the burning wood. 

Ordinary light-producing substances may be divided into 
solid, liquid, and gaseous. It is, however, the gaseous sub- 
stance in either case that burns and gives the light. In the 
solid candle, for instance, the fat of the candle is melted 

46 



LIGHTING 47 

by the heat radiated from the flame and becomes a liquid 
oil, and is then drawn up by capillarity into the wick, 
where a kind of distillation takes place and the oil is 
made into a gas which will burn. When any oil or liquid 
substance is burned in a lamp, it is already in a condition to 
be drawn up by capillarity, and is then volatilized as before. 
Illuminating gas is, however, delivered at the burner in a 
condition to be burned directly without any previous distil- 
lation, as that has already been done at the gas works. 

The ordinary candle flame illustrates very well the theory 
of combustion. It is divided into three zones : an inner zone 
of unburned gas ; a middle zone, where partial combustion 
takes place ; arid a third or outer zone of complete combustion, 
where there is very little light but much heat. It is in the 
second zone that the illumination takes place ; here the car- 
bon becomes incandescent or white-hot. The products of 
combustion are carbonic anhydrid and water, and as both 
these gases are transparent, they do not prevent the light 
from radiating outward. We are indebted to Michael Faraday 
for making a very thorough study of the nature of flame 
as long ago as 1835. In the candle flame the hottest point 
is at the end of the inner zone, and the interior of the flame 
is unburned gas. 

Experiment 23. Press down into a candle flame, for an 
instant only, a sheet of white paper, and notice the ring 
of carbon deposited on it. In a similar way a ring of car- 
bon may be deposited on a piece of glass, and the dark center 
of the candle can be seen on looking down inside the ring. 

Experiment 24. Blow out the flame of a candle that is 
burning with a long wick, and after an instant relight the 
smoke at a little distance from the end of the wick. The 
distillation of gas proceeds for some time after the candle is 
extinguished. 



48 SANITARY AND APPLIED CHEMISTRY 

Ordinary illuminating gas may be burned in the bat-wing 
or fish-tail burner to produce light ; or in the Bunsen burner, 
where there is enough air admitted into the bottom of the 
burner and mixed with the gas to give complete and rapid 
combustion, and consequently very little light. 

The earliest device for obtaining light was perhaps the pine 
knot or the torch, and this was followed by the rushlight, 
and the link, which was a rope saturated with pitch. After 
this came a crude lamp made by allowing a wick to fall over 
the edge of a dish containing some liquid fat and then a lamp 
in which the wick came through the hole in the side of the 
vessel or in the lip. There are many very beautiful lamps 
of these types found in ancient ruins. It was also found 
possible to make a solid light-giving substance, by drawing a 
piece of string through a lump of fat, and later this was 
modified by casting a solid fat around a wick, and thus the 
candle came into use. 

CANDLES 

The making of candles, by surrounding thin wicks of pith 
or flax with tallow or wax, dates from a very early period. 
In 1313 they are mentioned among the expenditures of the 
Earl of Lancaster. 1 Molded candles were introduced into 
England in the fifteenth century. 

Candles are made from tallow, stearin, paraffin, wax, and 
spermaceti. Although tallow has been in use for a long 
time, there are serious objections to it because the fat melts 
at such a low temperature and drips. What was needed, 
then, was a fat that had a higher melting point. This result 
was obtained by using a mixture of fatty acids produced 
from fats, instead of using tallow. 

Fats and oils are derived from both the vegetable and 
animal kingdoms. They are really compounds of organic 

1 Groves and Thorp, " Chemical Technology," Vol. II, p. 69. 



LIGHTING 49 

acids with bodies belonging to the group called alcohols; 
that is, they are glyceryl salts of organic acids, mostly of the 
"fatty acid" group. The alcohol is usually glycerol or 
glycerin, C 3 H 5 (OH) 3 , and the compounds are called glycer- 
ides. The acids most commonly found in these glycerides 
are stearic, palmitic, and oleic. Solid fats contain more of 
the glyceryl tri-stearate or " stearin" and the glyceryl tri- 
palmitate called " palmitin." The liquid fats consist largely 
of the glyceryl tri-oleate or "olein." (See Soap, p. 98.) 

Tallow contains 75% of stearin and olive oil only 25%. 
One of the best products used in candle making is made by 
heating tallow until it melts, and then when it is partially 
cold putting it in bags in piles under a hydraulic press and 
squeezing out the liquid fat. This will be more fully dis- 
cussed under Oleomargarine. 

There are several methods for separating the fatty acid 
from glycerin. This may be done by the use of steam, 
lime, and sulfuric acid. The commonest method is to 
heat under pressure with water, and a small percentage 
of lime or zinc oxid, and afterward to distill with steam. 
This affords the two products, stearic acid, which earlier in 
the process is separated by gravitation, and glycerin, which 
is carried over with the steam ; both of these are market- 
able. The stearic acid thus produced is quite crystalline, 
and indeed too much so to use alone in the manufacture of 
candles. In actual practice it is mixed with a little paraffin 
to prevent crumbling. 

There are two kinds of candles in use: dipped and 
molded. To make the former the wicks are dipped and 
allowed to cool and then repeatedly dipped again till the 
candle is large enough. A more modern method is to 
pour the melted fat into molds in which wicks have been 
previously suspended. Many attempts have been made to 
make a wick that will burn off at the end and not need 



50 SANITARY AND APPLIED CHEMISTRY 

snuffing. One of the best inventions in this line is the mak- 
ing of one thread of the wick shorter than the rest so that 
it will pull the wick over to one side where it is burned off. 
Paraffin is one of the last of the products obtained by 
the distillation of petroleum. (See p. 52.) Illuminating oils 
and lubricating oils distill over earlier in the process. 
Paraffin is in reality a mixture of hydrocarbons, having a 
high boiling point, and as it is a mixture it cannot be repre- 
sented by a formula. 

SPECIAL ILLUMINATING MATERIALS 

There were some other interesting illuminating materials 
in use in the United States between the 40' s and the 60's, 
before kerosene was produced. One of these was camphene, 
which was simply refined turpentine. Another, which was 
intended to remedy some of the defects of camphene and 
prevent some of the smokiness of the flame, was called 
" burning fluid," and was a mixture of turpentine and alco- 
hol. Various fixed oils, such as lard, whale, olive, colza, 
and poppy-seed, have been in use in lamps since the 
earliest times. Before the discovery and utilization of Petro- 
leum an oil, known as " coal oil," was obtained by the distil- 
lation of certain coals, and a " shale oil " was made by the 
destructive distillation of bituminous shales. 

KEROSENE 

Oil was first found in Pennsylvania in 1859 by Colonel 
Drake. 

Kerosene is one of the products that comes off in the 
distillation of petroleum or rock oil. This oil is obtained 
by boring to a depth of 600 to 1800 feet, and is frequently 
associated with natural gas. The product from a large num- 
ber of wells is carried by pipe lines hundreds of miles, 
even through a mountainous country, to a refinery. There 



LIGHTING 51 

are more than 3000 miles of these pipe lines from the oil 
regions of Pennsylvania and adjoining states to lake or sea 
ports. A barrel of oil moves forward every seven seconds, 
or at each stroke of the purnp which keeps the oil moving. 
In the process of refining, the oil is heated in immense 
retorts, and the more volatile products are distilled and 
condensed by passing through pipes surrounded by water. 
At a little higher temperature another product is given off, 
and another at a still higher, till at last a residue of paraffin 
remains, and this may be distilled off leaving only a small 
amount of coke in the retort. Often the distillation is car- 
ried on in two stages, the " light oils " being first distilled, 
and then the " heavy oils " in another still. 

DISTILLATES FROM PENNSYLVANIA PETROLEUM 

The commercial products obtained by the distillation of 
crude petroleum have various trade names, but the generally 
accepted classes of products are the following, beginning 
with the lightest: 1 — 

1. Cymogene, which is gaseous at ordinary temperatures. 
It may be used in the manufacture of artificial ice. 

2. Ehigolene, which may be condensed to a liquid by 
the use of ice and salt. It is used as an anaesthetic. 

3. Petroleum ether, which boils from 40° to 70° C. It 
is used as a solvent for caoutchouc. 

4. Gasolene, which boils from 70° to 90° C. It is used 
as fuel and in gasolene engines, forming an explosive mix- 
ture with air. 

5. Naphtha, which boils at 80° to 110° C. It is used 
in vapor lamps, and as a solvent for resins. 

6. Ligroine, which boils at from 80° to 120° C. It is 
used as a solvent. 

7. Benzine, which boils at 120° to 150° C. It is used as 
a substitute for turpentine, and as a solvent. 

1 "Industrial Organic Chemistry," Sadtler, p. 29. 



52 SANITARY AND APPLIED CHEMISTRY 

8. Kerosene or Burning Oil, which is graded by its color 
and " fire test." It has a flash test of 110° to 150° F. 

9. Lubricating oils, which have a gravity of from 32° 
to38°B. 

10. Paraffin, which is of different degrees of hardness, 
and like all the other products of variable composition. It 
is a solid, melting at from 51.°6 to 57.°3 C, and is used in 
candle making, in making water-proof papers, chewing 
gums, etc. 

The crude kerosene is purified by treatment with sul- 
furic acid and alkali, and subsequently by bleaching, in tanks 
with glass roofs. There is often a temptation to mix the 
lighter oils with the heavier, especially when the former are 
cheaper and there is not so much use for them. These light 
oils, however, increase the danger of explosions when the oil 
is burned in a lamp. If a vapor is given off at the ordinary 
room temperature in the summer, or the lamp is heated so 
that a vapor may be given off from the oil, it may be 
mixed with air in such proportions that an explosion will 
result. The following grades of burning oil are on the 
market : — 

110° Fire test (Standard white) 

120° " " (Prime white). 

150° " " (Water white). 

In many states and countries laws have been passed fixing 
the " flash point," or the " fire test," of oils, as it is called. 
By the " flash point " is understood the temperature at which 
a volatile vapor that will produce an explosion, is given off. 
The " fire test " is the temperature at which the oil will take 
fire and continue to burn. The laws of Ohio require a flash 
point not below 110° P. Those of New York require a 
higher point. In Kansas the requirement is the same as in 
Ohio, and the Foster cup is designated as the official tester. 



LIGHTING 53 

A simple flash-point apparatus may be made by the use 
of a small beaker filled about half full of kerosene, supported 
in a larger beaker or vessel containing water. The oil 
may be heated at a rate not faster than two degrees in a 
minute. Over the beaker containing the kerosene is placed 
a metallic cover, with a large opening in it. In this open- 
ing is -placed a thermometer, with the bulb in the kerosene. 
A very small flame is applied at the opening above the 
kerosene from time to time, and a record is made of the 
temperature at which the slight explosion of the gas ex- 
tinguishes the flame. This is the flash point. 

Experiment 25. Pour a small quantity of kerosene into 
a saucer, and touch a lighted match to it. The oil should 
not be ignited. 

Experiment 26. Pour about 2 cc. of gasolene into a sau- 
cer, and notice how readily it takes fire, and the smoky 
character of the flame. 

Experiment 27. Use a " Foster cup," or some convenient 
device as described above, for testing the flash point of sev- 
eral samples of kerosene. 1 

ILLUMINATING GAS 

Aside from natural gas, which has already been discussed 
under fuels, the gas used for lighting is either coal gas, 
water gas, air gas, Pintsch gas, or acetylene gas. 

Illuminating gas, known as coal gas, was discovered by 
Clayton in 1664, and used for lighting a dwelling in Lon- 
don, by William Murdock, in 1792. It did not come into 
general use, however, for many years, for London was not 
lighted by gas till 1812, and Paris in 1815. 

Gas is made by the distillation of soft coal in fire-clay 
retorts, heated to a cherry red by a fire of coke, which is 
1 B. Redwood, " Petroleum and its Products," Vol. II. 



54 SANITARY AND APPLIED CHEMISTRY 

maintained beneath them. In addition to the gas, there are 
several by-products made, including gas carbon, which is 
found attached to the inside of the retorts, coke, ammoniacal 
water, and coal tar. The injurious gaseous constituents, in- 
cluding the sulfur compounds, are removed from the gas 
by cooling, washing, and passing it through lime purifiers, 
and then the gas is stored in large gas holders, for distribu- 
tion through the city mains. A ton of coal will yield from 
8000 to 14,000 cu. ft. of gas. 

The gas carbon mentioned above is used in making elec- 
tric-light pencils and in batteries. The ammoniacal liquor is 
used for the manufacture of all the ammonia compounds of 
commerce. The coke is partly burned under the retorts, 
and the rest is sold as fuel, and finally the coal tar is dis- 
tilled to make an immense variety of valuable organic sub- 
stances, including many photographic developers, the aniline 
dyes, carbolic acid, oil of wintergreen, oil of " mirbane," sali- 
cylic acid, etc. 

Water gas is made by passing steam over incandescent 
coke or anthracite coal. This gives a mixture of the two 
gases, hydrogen and carbon monoxid, thus : — 

C + 2H 2 = C0 2 +2H 2 . 
C + C0 2 = 2CO 

These gases, however, give no light, and so the gas is en- 
riched by injecting into the generator, by means of a jet of 
steam, some crude petroleum, which at the high tempera- 
ture breaks up into volatile hydrocarbons, which furnish 
light when burned. On account of economy in manufac- 
ture, this gas is used instead of coal gas in many American 
cities. 

Air gas was much used for lighting detached buildings 
before electric-lighting plants could be so reasonably in- 
stalled. In this process air is forced through vessels con- 



LIGHTING 55 

taining gasoline, and some of the vapor is thus carried with 
the air into the pipes. What is burned then is really 
gasoline vapor. In order to avoid danger from fire, the 
liquid gasoline is stored underground outside the building. 

The method of making Pintsch gas, or oil gas, was in- 
vented in 1873, and it has found great favor as a compressed 
gas to use for lighting cars, steamboats, lighthouses, and 
isolated buildings. It is made from crude oil, by vapor- 
izing it in cast-iron retorts. The oil is " cracked " in 
the upper chamber of the apparatus, and the vapor is 
passed into the lower chamber which is heated nearly to 
1000° C. to " fix " the vapors and form permanent gases. 

Acetylene gas has come into use recently, since calcium 
carbid (CaC 2 ) has been made cheaply in the electric furnace 
by the use of powdered coke and lime. When calcium carbid 
is treated with water, acetylene gas is produced thus : — 

CaC 2 + 2 H 2 = Ca(OH) 2 + C 2 H 2 . 

This gas produces a very brilliant light, as there is much 
incandescent carbon in the flame. A burner which consumes 
only half a foot of gas per hour is usually the most efficient, 
especially when the gas is burned under considerable pres- 
sure. It is not safe to compress the gas to more than two 
atmospheres, as an explosion is liable to occur. The gas 
finds considerable use in country houses, on yachts, automo- 
biles, and bicycles. A ton of calcium carbid of 80% purity 
will produce 10,000 cu. ft. of acetylene gas. 1 

Illuminating gas gives the best results when burned at a 
water pressure of not over 1± in. If the pressure is too 
great the gas " blows" and the light is decreased. The 
amount of gas burned in an ordinary burner is from 2 to 
8 cu. ft. per hour, dependent on the rating or size of the 

1 Thorp, " Outline of Industrial Chemistry," p. 293. 



56 



SANITARY AND APPLIED CHEMISTRY 



burner and the pressure of the gas. A comparison of the 
coal, water, oil, and natural gas may be made by inspection 
of the following analyses : — 





Coal 


Water 1 
(Carbureted) 


PlNTSCH OR 

Oil* 


Natural Gas 


Carbon dioxid . . 


1.22 


3.00 





.25 


defiant gas, etc. 


5.30 


16.60 


45.00 


.35 


Carbon monoxid 


7.50 


26.10 





.41 


Marsh gas .... 


38.11 


19.80 


38.80 


93.35 


Nitrogen .... 





2.40 


1.10 


3.41 


Oxygen .... 


.22 








.39 


Hydrogen .... 


47.65 


32.10 


16.60 


1.64 


Ethane 








14.60 






From these analyses it is evident that water gas, if breathed, 
would be the most liable to produce death, since it contains 
the most carbon monoxid. Natural gas contains less than 
coal gas. 

Experiment 28. Test coal gas for carbon dioxid, by pass- 
ing it through lime water contained in a Woulff bottle. For 
this purpose, put through a hole in one cork a tube bent at 
a right angle, with one limb extending to the bottom of the 
bottle, and through a hole in the other cork a tube of the 
same size, bent at a right angle, and passing just through 
the cork. Fill the bottle half full of lime water, allow the 
gas to bubble slowly through this, and light the gas that 
escapes. After a time, dependent on the amount of carbon 
dioxid in the gas, there will be a deposit of calcium carbon- 
ate in the bottle. 

Ca(OH) 2 + C0 2 = CaC0 3 + H 2 0. 

1 Thorp, " Outline of Industrial Chemistry," p. 294. 



LIGHTING 57 

Experiment 29. To test the gas for hydrogen sulfid, 
allow a slow stream to pass through the empty Woulff bottle 
arranged as above, in which is suspended a piece of filter 
paper which has been dipped in a solution of lead acetate. 
The paper will turn brown or black after a time on account 
of the formation of lead sulfid on the paper. 

Experiment 30. To test the pressure of the coal gas used, 
the apparatus mentioned in Experiment 29 may be used. If 
the bottle is small, a straight tube about eight inches (20 cm.) 
long may be put in to take the place of the longer bent tube. 
Fill the bottle about one third full of water. Attach the 
gas to the shorter tube, and measure the height of the col- 
umn of water raised by the pressure of the gas. 

Experiment 31. Learn to read a gas or water meter. The 
figures on the dial having the highest number are read first, 
and in case a pointer is very nearly upon any figure, notice 
by reference to the next lower dial whether it is above or 
below that figure, and read accordingly. 

Experiment 32. To make acetylene gas, put a small quan- 
tity of calcium carbid in a test tube. Place this in a rack 
or a test-tube holder, and carefully bring into the tube a 
few drops of water. The gas will be immediately given off 
and may be lighted. 

Experiment 33. To make an acetylene lamp use a heavy 
16 oz. flask provided with a cork having two holes. In one 
of these holes put a dropping funnel, with the tube extend- 
ing nearly to the bottom of the flask, in the other hole a tube 
bent at a right angle. Place about an ounce of calcium 
carbid in the flask, and allow water to drop on it, a very small 
quantity at a time, by the use of the dropping funnel. Pass 
the gas evolved through another flask or Woulff bottle 
containing some lumps of calcium carbid ; this will dry the 
evolved gas. In one tubulature of the drying bottle put a 



58 SASTCTARY AND APPLIED CHEMISTRY 

straight tube, to the top of which is fitted, by a short rubber 
tube, a special lava tip designed for burning acetylene gas 
which uses one half a foot of gas per hour. A brilliant 
light will be obtained. 

Experiment 34. In the incomplete composition of illumi- 
nating gas small quantities of acetylene are formed. Study 
the phenomenon which takes place when a Bunsen burner 
"strikes back" and burns at the base. 

LAMPS AND BUHNERS 

A great variety of devices have been used to utilize oils 
and gas and get the greatest possible illuminating value from 
them. With a lamp, where kerosene or some oil is used as 
the combustible, the glass chimney came into use to increase 
the draft, and prevent smoking. If the substance burned is 
rich in carbon, as is the case with gasoline (Experiment 26), 
this is particularly necessary. Another device to attain the 
same end that has been used in lighthouses is the use of a 
pump, run by clockwork, to keep the wick, especially of a 
large lamp, saturated with oil. A blower, concealed in the 
base of the lamp, has also been introduced, to avoid the use 
of a chimney. 

The invention of the Argand lamp in 1786, which was 
applied both to oil and gas, and in which the air enters the 
inside of the circular flame, was a distinct advance in illu- 
mination. The student lamp is of this type. The flat flame 
of the gas burner is obtained either in the " bat-wing " tip or 
the "fish-tail" burner. In the former, the gas comes out 
through a lava tip, which has a narrow slit in the top ; in 
the latter, the gas comes out through two opposite openings, 
usually in a metallic tip, and the resultant of these two cur- 
rents of gas is a flat flame, at a right angle to the currents 
of gas. 



LIGHTING 59 

INCANDESCENT GAS LIGHTS 

On account of the fact that much of the gas in common 
use is of low candle power, and yet has great " fuel value/' 
numerous attempts have been made to utilize this heat to 
produce light. Passing over many of the systems in use, 
the most practical at the present time is the Welsbach sys- 
tem. This was invented by C. Auer von Welsbach in 1885- 
1887. This lamp consists of a Bunsen burner over which is 
suspended a " mantle " of the oxids of such rare earths as 
cerium, lanthanum, thorium, yttrium, or zirconium. A 
cylinder of cotton is soaked in the nitrates of these metals, 
and one end is gathered into a ring. After it has been dried 
the cotton is burned off, and the oxids are worked into 
shape upon a form. Then, in order to preserve this fragile 
material, it is plunged into a bath of collodion, paraffin, or 
some similar substance which stiffens it. This latter ma- 
terial is burned off when the mantle is put in place over the 
Bunsen burner. The " life " of these mantles is from 500 
to 1000 hr., and even if they have not become ruptured, 
after a time their candle power is very much lowered. In 
one experiment when burning 2.5 cu. ft. of gas per hour, at 
one inch pressure, 25.6 candle-power was obtained at first, 
after 500 hr. only 18 candle power, and at the end of 1000 hr. 
13.7 candle power. 

This kind of burner, which is designed to utilize the heat 
of the gas, produces a high candle-power light, uses a mini- 
mum of gas, and is satisfactory with natural gas, water gas 
that has not been carbureted, or any gas that is a poor light 
producer. 

Experiment 35. To show the principle of light due to an 
incandescent solid burn a piece of magnesium ribbon, or, 
better still, heat a piece of calcium oxid in the flame of the 
oxyhydrogen burner. 



60 SANITARY AND APPLIED CHEMISTRY 

ELECTRIC LIGHTS 

In the modern method of lighting by electricity the com- 
mon systems are the use of the arc light, in which pencils 
of gas carbon are heated by the electric current ; the incan- 
descent, in which a filament of carbon contained in a bulb 
from which the air has been fully exhausted is heated by 
the passage of the current ; the tantalum lamp, in which the 
metal tantalum is used as the incandescent material; the 
inclosed arc; the mercury vapor lamp; and the Nernst 
lamp. In most of these some highly heated solid gives out 
the light. 

Most of the lights that have been mentioned are, at the 
best, wasteful, because we get heat and comparatively little 
light, when light and not heat is desired. A recent author 
says that 99% of the energy of the candle flame and 50% 
of that of the electric light does not appear as light. This 
energy is not only wasted, but as it appears in the form of 
heat, it is often a source of great inconvenience. Experi- 
ments have been made on the phenomenon of phospho- 
rescence, and on the light of the firefly, that show how much 
superior this is to any light devised by man. There seems 
to be no reason why man cannot hope to perfect some system 
of lighting that shall be as economical, and this is no doubt 
the light of the future. 



CHAPTER V 
WATER 

As water is so essential to human life, it is evident that a 
study of its occurrence and liability to contamination may 
be undertaken with great profit. It is composed of two 
simple elements, hydrogen and oxygen, both invisible gases, 
and the purest water is, of course, that which is formed by 
the union of these gases. 

Water, when it is condensed in the clouds, is compara- 
tively pure, and as it falls through the atmosphere it dis- 
solves certain gases that are present in the air, and at the 
same time washes the air free from suspended organic and 
inorganic dust. We are familiar with practically pure 
water in the form of distilled water, which is odorless and 
tasteless but to many is not agreeable as drinking water, 
because it does not contain the dissolved gases of the atmos- 
phere nor the mineral salts to which they are accustomed. 
If it is aerated by shaking with air and a very small quan- 
tity of salt is added, it becomes much more agreeable as a 
beverage. 

Natural waters may be divided into : rain water, which 
we collect in cisterns, spring water, brook, river, lake, well 
(both shallow and artesian), and, finally, sea water. There 
is another class of waters, which are especially interesting 
from a medicinal standpoint, viz. mineral waters. 

Cistern water may be collected practically pure, if it falls 
on a metallic or slate roof which is washed off with the first 
water of a rain, allowing this to waste. A well-painted 
shingle roof may also be used for collecting the water if 

61 



62 SANITARY AND APPLIED CHEMISTRY 

sufficient care is exercised in washing the roof. The water 
of a cistern should be aerated by the use of some kind of 
a chain or bucket pump that will carry air into the water. 
This may be used as an auxiliary means of obtaining water 
from the cistern, even if an ordinary suction pump is used 
for domestic supply. 

Spring water, when it has flowed through sandstone or 
granite in an unpopulated region, is usually pure and free 
from mineral matter. In limestone countries, however, 
spring water is liable to become loaded with the mineral 
substances of the rocks and soil through which it perco- 
lates; and on some of the alkali plains it becomes very 
strongly impregnated with mineral matter. There is a con- 
stant tendency for the mineral matter to concentrate in 
river water, and these waters, which contain the soluble 
materials of the soil, finally accumulate in the ocean. Dilu- 
tion with nearly pure surface waters often prevents river 
water from increasing in mineral salts. The gases of the 
atmosphere, especially the carbon dioxid, assist very mate- 
rially in the solution of some of the rocks. Spring water 
may also contain organic matter from peat swamps, which 
usually gives it a brownish color. 

Eiver water partakes of the character of the springs and 
brooks which feed it, and it is also liable to become con- 
taminated from refuse and sewage which is poured into 
it from inhabited regions. As a large stream is so often 
used to carry off the " waste of civilization," in the form 
of sewage, it is seldom, in a well-populated district, that 
river water can be used with safety as a source of supply 
without some preliminary treatment by filtration. 

The water of the Great Lakes would be of the very best 
quality were it not for the fact that it is difficult to dispose 
of the sewage of the cities on the banks without contaminat- 
ing the water supply. This difficulty has been partially 



WATER 63 

overcome, in many instances, by tunneling out several miles 
under the lake to an " intake " to get water uncontaminated 
by the city sewage. In the case of Chicago, by pumping the 
water containing the sewage through a drainage canal away 
from the lake into the Illinois river, the water supply 
is protected. 

The water of wells will be pure or impure as the soil 
around them is pure or contaminated. Generally speaking, 
the water of bored and cased wells is purer than that of 
ordinary, shallow, dug wells, and the water of artesian wells, 
especially those which penetrate the earth to the depth of 
from 300 to 1000 ft., is usually better than that from shallow 
wells. As an ordinary well is but a hole in the ground, it 
naturally collects the surface impurities in the vicinity, and 
in cities and large towns this water is liable to be very im- 
pure. It may contain mineral salts, but the most dangerous 
impurities are of an organic nature. The character of these 
organic impurities is significant, as it is a key to the past 
history of the water and often reveals the fact that it has 
percolated through soil contaminated with sewage or the 
waste material from cesspools. 

Although the water of wells is liable to be impure from 
cracks in the soil through which the foul water of drains or 
cesspools has entered, yet a commonly neglected source of 
infection is the surface drainage that may find its way into 
the well, because it is not carefully covered. When the 
water is pumped out and allowed to fall on dirty planks, 
where chickens and other animals resort, there is every 
opportunity for contamination. The same remark applies 
to cisterns, which sometimes receive not only the drainage 
of the soil, but of the dooryard where all the slops from the 
house are thrown. 

Artesian well water is usually free from dangerous or- 
ganic matter. The term " artesian," a name derived from 



64 SANITARY AND APPLIED CHEMISTRY 

the province of Artois in France, where these wells were 
first used, applies strictly speaking to deep, flowing wells. 
In the United States there is a large area in northern 
Florida, and one in the vicinity of Charleston, South Caro- 
lina, where an abundance of water is supplied by artesian 
wells. In the city of Memphis, Tennessee, where some 
years ago there was an epidemic of yellow fever, great pains 
has been taken to obtain pure artesian water from deep 
wells. The analysis of this water, which was made some 
years ago by the author, showed it to be exceptionally pure, 
and the health of the city has been very much improved 
since its introduction. Some artesian wells have penetrated 
to such a depth or through such strata, that the water be- 
comes impregnated with too much mineral matter, so that it 
cannot be used for domestic purposes. This is the case, 
for instance, with a well bored at St. Louis to the depth 
of over 2000 ft. for supplying a brewery. The water con- 
tained so much salt that it could not be used. 

MINERAL WATERS 

Mineral waters are those which contain an excess of 
some ordinary ingredients, or small quantities of some rare 
ingredients, and which on this account are used as remedial 
agents. There are besides these certain waters on the market, 
known as " table waters, " which are simply very pure, and 
are recommended by physicians because they may be taken 
in large quantities and will not affect the system by any 
minerals which they contain. 

I. MINERAL SUBSTANCES IN WATER 

Some of the mineral substances found in natural waters 
and in mineral waters are the following : sodium, calcium, 
magnesium, iron, aluminum, lithium, and potassium, com- 



WATER 65 

bined as silicates, sulfates, chlorids, carbonates, and some- 
times as borates and arsenates. Common mineral substances 
in waters may be tested for as follows : In making the tests 
for mineral substance in water, it is advisable to first test 
the water supply of the laboratory, and if it does not con- 
tain the substance tested for, then use a strong mineral water 
of known composition, like Apollinaris, Hunyadi-Janos, or 
Congress water. 

Experiment 36. Test for calcium in water that does not 
contain much iron by adding to it some ammonium chlorid, 
ammonium hydroxid, and ammonium oxalate. The forma- 
tion of a white precipitate of calcium oxalate, especially 
after boiling, indicates the presence of calcium. 

Experiment 37. Test for magnesium by first filtering off 
the calcium oxalate, if any is precipitated in the previous 
experiment, and adding to the filtrate, which should contain 
some ammonium chlorid and ammonium hydroxid, hydrogen 
sodium phosphate. The formation of a white crystalline 
precipitate of ammonium magnesium phosphate, especially 
upon shaking, indicates the presence of magnesium. 

Experiment 38. Test for iron as a ferric compound by 
adding a few drops of hydrochloric acid and some potassium 
ferrocyanid. The formation of a dark blue precipitate (Prus- 
sian blue) shows the presence of ferric salts. To test for 
ferrous salts, add to some of the water a few drops of 
hydrochloric acid and potassium ferricyanid. The forma- 
tion of a blue precipitate indicates the presence of ferrous 
compounds. 

Experiment 38 a. Another excellent test for ferric com- 
pounds is to add to a slightly acidified sample of the water 
a few drops of potassium sulfocyanate. The production of 
a red color indicates iron. 



66 SANITARY AND APPLIED CHEMISTRY 

Experiment 39. Test for aluminum by adding to the water 
a few drops of ammonium chlorid and ammonium hydroxid 
in excess. The formation of a white flocculent precipitate, 
especially upon warming and allowing the solution to stand, 
indicates aluminum. In the presence of a considerable quan- 
tity of a ferric compound, the iron will be thrown down as a 
reddish precipitate, thus obscuring the aluminum hydroxid 
precipitate. 

Experiment 40. To test for lead add to a sample of water, 
acidified with hydrochloric acid, a little hydrogen sulfid 
water. The formation of a black or brownish coloration 
will indicate lead. 

Experiment 41. In order to show how readily water, espe- 
cially when pure, attacks lead, scrape a piece of sheet lead 
till it is bright and clean. Place this in a beaker of distilled 
water, and allow to stand for an hour or more. Kemove the 
lead from the water and test the water for lead by the use 
of hydrogen sulfid water. 

Experiment 42. Test for sulfates by acidifying a sample 
of the water with hydrochloric acid, and adding a few drops 
of barium chlorid. The formation of a dense white precipi- 
tate of barium sulfate, especially after boiling, indicates the 
presence of sulfates. 

Experiment 43. To test for chlorids, add a few drops of 
nitric acid to the sample, and then silver nitrate. The 
formation of a white precipitate of silver chlorid indicates 
chlorids. 

Experiment 44. To test for the total amount of mineral 
matter in the water, evaporate from 100 cc. to 200 cc. in a 
weighed porcelain or platinum dish on a water bath. Dry 
the residue at 120° C, and weigh. Calculate the weight in 
terms of grams per liter. (The dish can be weighed on the 
ordinary horn-pan balance.) 



WATER 67 

Experiment 45. To test for carbonates, add a few drops 
of hydrochloric acid to the residue obtained in the previous 
experiment. If carbonates are present there will be an 
effervescence on account of the escape of carbon dioxid gas. 
This solution may then be tested for potassium and sodium 
by dipping into it a platinum wire, which is heated in the 
Bunsen burner and the flame can be examined with the 
spectroscope. 

Experiment 46. To test for sulfur or hydrogen sulfid in 
a water like that from sulfur springs, plunge a silver coin 
into the water, and in the presence of soluble sulfids it will 
be quickly blackened on account of the formation of silver 
sulfid, Ag 2 S. 

HARD WATERS 

Some waters contain large quantities of calcium, magne- 
sium, iron, and aluminum. Those which contain these 
metals associated with the carbonate radical making calcium 
acid carbonate, magnesium acid carbonate, etc., are called 
temporarily hard waters, and those which contain calcium, 
magnesium, iron, or aluminum sulfates or chlorids, are called 
permanently hard waters. This distinction is made because 
the carbonate waters can be readily softened by adding to 
them lime water in sufficient quantity, while it is much more 
difficult to soften the permanently hard waters. Another 
reason for this distinction is that a considerable quantity of 
the mineral matter is precipitated by boiling, in accordance 
with the equation : — 

CaH 2 (C0 3 ) 2 + heat = CaCQ 3 + C0 2 + H 2 0. 

The difference between the hard and soft water may be 
readily shown by the action upon the two varieties of a soap 
solution. 

Hard waters produce serious inconvenience when used in 
steam boilers, depositing a scale of greater or less thickness, 



68 SANITARY AND APPLIED CHEMISTRY 

which causes great loss of fuel by interfering with the 
transmission of heat to the water, and is liable, if it becomes 
thick enough, to allow the iron to become overheated, and 
greatly increase the tendency to explosion. The same kind 
of a scale is often found in a tea kettle when hard water is 
used. There is an immense advantage in substituting soft 
water for hard when the item of soap is considered. It is 
estimated that in Glasgow, where the soft water of Loch 
Katrine was substituted for hard water, there was a saving 
in soap to the inhabitants of the city of nearly $200,000 
annually. It is supposed that hard waters sometimes cause 
diseases, like goiter. There are some districts in India 
where 10% of the people are afflicted with this disease, 
and it has been noticed that the water used there is strongly 
calcareous. Kecent investigations by Walters 1 led him to 
believe that goiter is due to an organism of the amoeba type, 
found in the water rather than to the presence of mineral 
salts. The table on p. 73 shows the amount of mineral 
matter (total residue) in some city supplies in the United 
States. 

Experiment 47. Prepare a sample of very hard water by 
adding considerable calcium chlorid to a sample of ordinary 
water, and pour this into a tall cylinder. Add to this some 
soap solution, 2 shake thoroughly, and notice how many cubic 
centimeters of the soap solution must be used before a per- 
manent lather is produced in the water. Compare this with 
a similar experiment made with soft or distilled water. No- 
tice also the abundant precipitate of " lime soap " in the hard 
water. 

1 British Medical Journal, 1897. 

2 To make a soap solution Mason (" Water Supply," p. 360) recom- 
mends to use 10 g. of Castile soap, scraped into fine shavings, and 
dissolved in a liter of alcohol diluted with one third water. Filter, if 
not clear, and keep in a tightly stoppered bottle. 



WATER 69 

II. ORGANIC MATTER IN WATER 

The mineral constituents of water: those which give 
character to the so-called mineral waters, which make water 
hard, which give saltness to brine, and the peculiar charac- 
teristics to the " alkali" waters of the plains, have been pre- 
viously discussed. There are, however, other substances in 
waters which it may not be possible to detect there either 
by the sense of taste, smell, or sight, and yet these sub- 
stances, which constitute the " organic matter," are from a 
sanitary standpoint of the greatest importance. 

As has been stated the mineral matter comes from the de- 
composition of the rocks and of the soil through which the 
water percolates. In a similar way, the organic material 
comes from the soil through which the water passes, or over 
which it runs. It is difficult to tell the source of the organic 
matter from a simple analysis of the water. It may come 
from peat swamps in which decomposing vegetable matter 
has remained for a long time in contact with the water ; it 
may come from the decayed leaves or wood ; or, what is 
much worse, it may be from decomposed animal matter, 
which finds its way into a stream or well from some cesspool 
or barnyard or foul kitchen drain. 

The chemist in making a sanitary analysis of a water deter- 
mines its color, odor, and turbidity, as well as the residue 
left on evaporation, loss on ignition of this residue, free 
ammonia, albuminoid ammonia, nitrogen present in nitrites, 
nitrogen present in nitrates, chlorin, oxygen consuming 
power, and hardness. From a consideration of all this 
data ; from a knowledge of the locality from which the 
water comes ; from comparisons with other waters from the 
same locality, all together he is able to form an opinion 
as to whether the water is safe for domestic use. A bac- 
teriological examination will also be of value in estimating 
the character of the water. 



70 SANITARY AND APPLIED CHEMISTRY 

The ammonia is not in itself injurious, but is an index of 
nitrogenous matter, which is liable to be dangerous. When- 
ever there is matter of this kind, bacteria find the conditions 
suited to their growth, and some of these may be pathogenic 
in character and so are liable to produce disease. 

Free ammonia is usually considered to be indicative of 
recent contamination, especially of animal origin, while 
albuminoid ammonia indicates more especially nitrogenous 
matter that has not undergone sufficient decomposition for 
the formation of ammonia compounds. If the water 
changes in its ammonia content from day to day, this also 
shows that it is in a dangerous condition. As to the amount 
of these substances which may be allowed in a good water, 
it is practically impossible to set a standard, as local condi- 
tions are so variable. What would be a fair standard for a 
water from one source, would not apply at all to water of 
a different character. Professor Mason reports an excellent 
mountain stream as containing as high as .055 parts of free 
ammonia and .230 of albuminoid ammonia per million. 
Professor Mallet reports the average of a number of city 
supplies considered good as containing .152 parts of albumi- 
noid ammonia, and Professor Leeds would limit the 
amounts to free ammonia .01 to .12 per million and albumi- 
noid ammonia .10 to .28 per million. 

Pree ammonia is determined in a water by distilling a 
half liter and testing the several portions of 50 cc. of the 
distillate with Nessler solution. The brown color produced 
is compared with that obtained in solutions of ammonia of 
known composition. Wlien the free ammonia has been 
distilled off, some alkaline permanganate solution is added, 
and the ammonia thus set free on distillation is determined 
as before. This is the albuminoid ammonia. 

The nitrites in water are indicative of a changing con- 
dition of oxidation, which is completed when the nitroge- 



WATER 71 

nous bodies are changed to nitrates. The determination of 
nitrates is considered of value in supplying some data as to 
the previous history of water. If the nitrates are abundant 
this indicates that at some earlier stage in the history of the 
water it may have been contaminated with sewage, and 
although there may be no free ammonia present, we have 
no proof that the pathogenic germs, that once existed in the 
water, are destroyed by the oxidation which the ammonia 
has undergone. 

In regard to the nitrates, it is evident that there must be 
some of these in natural waters, for both nitrites and nitrates 
are washed out of the air and carried into the soil, and we 
depend upon the nitrates as well as other nitrogenous com- 
pounds in the soil to assist in the growth of plants. The 
determination of nitrates is regarded by Mallet as of great 
importance, and he places the figures for the amount as 
averaging 0.42, the extreme limit being 1.04 parts per million. 
He notices that waters known to be polluted contain sometimes 
from 7.239 to 28.403 parts of nitrogen as nitrates per million. 
The average for American rivers is given as from 1.11 to 3.89 
parts per million, and the author has found in city wells 
from 14.5 to 30 parts per million of nitrogen as nitrates. 

The Rivers Pollution Commission (Eng.) gives the follow- 
ing averages from 589 unpolluted waters for nitrogen as 
nitrites and nitrates. 

Paets pek Million 

Rain water 03 

Upland surface 09 

Deep well .... . . 4.95 

Spring 3.83 

In some localities the determination of chlorin may be of 
value, especially where the normal chlorin content of the 
ground water is known. The soil of several of the New 
England states has been thoroughly studied, the normal 



72 SANITAKY AND APPLIED CHEMISTRY 

amount of chlorin for each, locality has been pretty accu- 
rately determined, and a map has been prepared showing 
where equal amounts of chlorin are found. An increase in 
chlorin would show probable pollution with sewage. In 
many places, however, there is so much salt in the soil that 
the determination of chlorin is of no value. 

Experiment 48. To make Nessler's solution, dissolve 8 g. 
of mercuric chlorid, HgCl 2 , in a quarter of a liter of pure 
water. Dissolve 17 g. of potassium iodid, KI, in 100 cc. of 
pure water. Pour the first solution into the second until a 
slight permanent precipitate, which does not disappear on 
shaking, is produced. Add 80 g. of solid potassium hy- 
droxid, KOH, dilute to one half a liter, cool, and add drop by 
drop some of the mercuric chlorid solution till there is a 
slight permanent precipitate. Allow to settle for some time, 
and pour off the clear yellowish solution for use. The old 
"Nessler " is better than one which is recently made. 

Experiment 49. Test a sample of the distilled water used 
in the laboratory for ammonia by placing some of it in a long 
test tube, or a so-called Nessler tube, standing on a piece of 
white paper, and adding to it 2 cc. of Nessler solution. 
Notice the brown tint of the solution. 

Experiment 50. Distill about 500 cc. of well or river water 
slowly from a liter retort, condense the steam in a flask float- 
ing in a pan of water, and test about 50 cc. in a long tube by 
adding 2 cc. of Nessler solution, and allowing the mixture to 
stand a few minutes. Unless the water is very pure, there 
will be a distinct brown coloration. 

Experiment 51. To test for nitrates in water, add to about 
10 cc. in a test tube an equal quantity of concentrated sul- 
furic acid and cool the solution. Then add to this cau- 
tiously, without mixing, a strong solution of ferrous sulfate. 
The formation of a brown ring where the two liquids come 



WATER 



73 



together indicates the presence of nitrates. This test is 
delicate only to about ten parts of nitric acid in a million 
parts of water. A very small crystal of saltpeter, potassium 
nitrate, may be used in the water to show the test. 

Experiment 52. To test for organic matter when present in 
large quantity, add to a sample of water, contained in a tall 
stoppered cylinder, a little dilute sulfuric acid and a few 
cubic centimeters of a 1 % solution of potassium permanganate. 
The purple color of this solution is discharged by shaking with 
water containing organic matter, so the amount of organic 
matter may be estimated relatively by noticing how much 
permanganate must be used to produce a permanent purple 
color in the water. (This same reagent may be used prac- 
tically on a large scale to remove the foul odor of cistern 
water. Potassium permanganate should be added to the 
water until, on mixing, there is a slight pink tint to the 
water.) 

Analysis of City Water Supply l 
(Parts per Million) 



Springfield, Mass., Aver. 1893 

Boston, " " 1894 

Burlington, Vt. (Lake Cham plain) 

Poughkeepsie, N.Y. (Hudson E.) 

Eock Island, 111. (Miss. E.) 

New Orleans, La. (Miss. E.) 

Charleston, S.C. (artesian well) 

Brooklyn, N.Y. (ground water) 

Cincinnati, Ohio (Ohio E.) 

Philadelphia (Schuylkill E., average of 22) 
New York, weekly average for 1894 



.009 
.006 
.035 
.050 
.025 
.040 
.300 
.001 
.003 
.010 
.012 



32 



.204 
.319 
.140 
.125 
.260 
.325 
.040 
.085 
.108 
.100 
.082 



1.50 
4.10 
0.T0 
4.50 
1.00 
14.50 
130.00 
13.50 
14.00 

2.47 



< S 



.001 
.001 

trace 





£ » 



.026 

.106 

trace 

trace 

trace 

.080 



16.000 

.260 

.460 

.258 



So 



5.132 
6.295 
1.525 
2.287 
6.000 
5.724 
2.043 



Ms 



37.6 

46.4 

70.0 

85.0 

140.0 

340.0 

1170.0 

64.0 

140.0 

133.4 

81.6 



1 " Water Supplies," Mason, p. 465. 



74 SANITARY AND APPLIED CHEMISTRY 



DRINKING WATER AND DISEASE 

It should be noticed in the first place that while 
peaty waters contain quite large quantities of organic 
matter, this is not considered as injurious as other kinds 
of organic material. The best authorities seem to agree, 
however, that its presence does tend to induce diarrhoea 
and malaria. According to recent investigations the preva- 
lence of malaria in certain localities is due largely to the 
low land and numerous puddles where the mosquitoes that 
transmit the infection have a chance to breed. 1 It should 
also be said that though a water of this class may be harm- 
less at some stages of its history, at other stages it may be 
injurious on account of the decomposition that has taken 
place. Another water containing a large quantity of organic 
matter is the so-called sawdust water, which is obtained 
from wells sunk in " made " land in the vicinity of streams 
where sawmills have been located. This is, without doubt, 
injurious. 

In regard to hard waters, the opinion seems to be pre- 
dominant that the mortality is practically uninfluenced by 
hard or soft water. 

In many localities, waters that are extremely turbid are 
used for domestic purposes, and it is evident that they are 
used without serious injury, when we consider the popula- 
tion and the death rate in such cities as Cincinnati, Louis- 
ville, and St. Louis. This should be said, however, that 
while these waters are used with impunity by those who are 
accustomed to their use, strangers are frequently affected 
seriously for a time by the use of such waters. 

A much more serious class of impurities is those which 
come from the introduction of sewage into the waters, and 

1 " Practical Hygiene," Harrington, p. 649. 



WATER 75 

although they may be perfectly clear, transparent, and of 
good taste, such waters are often extremely dangerous. The 
question arises, Shall the water once polluted by sewage be 
again used for human consumption ? And if there is danger 
in such use, What is its extent, and can such danger be 
avoided ? A few examples of pollution of water by sewage 
will be of interest. 

In 1887 x the city of Messina, Sicily, was visited by an 
epidemic of cholera. From September 10 to October 25 
there were 5000 cases and 2200 deaths. The government 
investigated this epidemic, and it w T as found that though 
the water which was supplied to the city left the gathering 
grounds in the mountain of good quality, part of it was 
diverted on its way to the city, and used by the washer- 
women of the vicinity for washing clothes, and was after- 
ward conducted back into the open canal which supplied 
the city. As soon as the authorities sent tank ships to the 
mainland and obtained pure water for use in the city, the 
plague ceased as if by magic. 

In 1890 there were two violent epidemics of typhoid fever 
in the valley of the Tees in England. The country which 
supplied the water was not thickly populated, and the water 
was apparently good. It was found, however, that many 
of the towns discharged their sewage into the stream, and 
in dry weather the stream receded, leaving its banks dry 
and exposed. Here the filth accumulated, and in times of 
high water this was swept into the stream, and was after- 
ward pumped into the reservoirs and used as the source of 
water supply. It was noticed that an " increase of rainfall 
was followed by an increase in the number of cases of 
typhoid fever among those persons using the Tees water, 
after an interval corresponding to the incubation period 
of the disease, while no appreciable result was noticed 

1 Mason on " Water Supply," p. 24. 



76 SANITARY AND APPLIED CHEMISTRY 

among those people of the district using other sources of 
supply." 1 

One of the most interesting cases is that of the city of 
Plymouth, Pennsylvania, containing 8000 population. In 
a few weeks there were more than 1000 cases of typhoid 
fever and 100 deaths. The water supply was obtained 
from a mountain brook. There were but few houses on the 
banks of this brook, and it would seem that the water was 
well protected from sources of contamination. On investi- 
gation, it was learned that while the stream was frozen a 
man had been sick with typhoid fever, and had been cared 
for in a house near the source of this mountain brook. The 
discharges were thrown upon the snow, and when this 
melted in the spring the filth was swept into the stream. 
The inhabitants of the village of Plymouth were obliged to 
use this water for a time as their source of supply, instead 
of the Susquehanna Eiver, so the typhoid poison was 
pumped to all parts of the city. It was noticed that whole 
groups of families using well water escaped entirely, while 
those using the city water were afflicted with typhoid fever. 
It was estimated that aside from the deaths that occurred, 
the money losses to this community in wages and care of the 
sick was over $100,000. 

All are more or less familiar with the conditions at the 
time of the terrible outbreak of cholera in Hamburg, Ger- 
many, in 1892. The city had a population of 640,000. The 
epidemic lasted for about three months, and the total num- 
ber of cholera cases was 17,000, with 50% mortality. Ham- 
burg is close to the city of Altona ; in fact, these two together 
with Wandsbeck are practically one city, but they obtain 
their water from different sources. Hamburg pumps water 
from the Elbe Eiver, the intake being just south of the city. 
Altona pumps its water from the Elbe at a point about 8 

1 Mason on " Water Supply," p. 27. 



WATER 77 

miles below that at which the river receives the sewage of 
the three cities ; but in the case of Altona the water which 
has received the sewage from a population of 800,000 people 
was filtered with exceeding care before being delivered to 
the people. It was interesting to notice in this case that in 
some sections of the city, people supplied with the Hamburg 
water were afflicted with cholera, while those on the other 
side of the same street using the Altona water were not 
afflicted, and this immunity from cholera of those using the 
Altona water was noticeable all over the city. 

The analysis of the Hamburg supply showed in parts per 
million : — 

Free ammonia 1.065 

Albuminoid ammonia .293 

Nitrates 26.430 

Chlorin 472.000 

The case of the outbreak of typhoid fever at Lausen, 
Switzerland, is also very instructive. The source of the 
epidemic was traced to an isolated farmhouse on the oppo- 
site side of the mountain, where three cases of the fever 
occurred. The brook which ran past the house was after- 
wards used for irrigating some meadows, and then filtered 
through the intervening mountain to a spring in Lausen, 
from which all the people, except those in six houses, ob- 
tained their water supply. In the six houses no cases of 
fever occurred, but scarcely one of the other houses escaped. 
By dissolving a large amount of salt in the water on the 
other side of the mountain, and observing the great in- 
crease of chlorin in the spring water, the source of the in- 
fection was traced, and to show how thoroughly the water 
was filtered, a quantity of flour was mixed with the brook 
water, and not a trace was found in the spring water at the 
village. This showed that filtration through the rocks and 
soil of the mountain did not remove the dangerous infection. 



78 SANITARY AND APPLIED CHEMISTRY 

The water of our ordinary domestic wells is also liable to 
be impure, especially in a thickly populated district. Ma- 
terial from cesspools or vaults or sewers or even from the 
surface may get in and contaminate the water. The chief 
trouble is that we cannot be sure of the water, for as a dis- 
trict becomes more thickly populated there may come a 
time when the soil is saturated with filth, and then every 
rain will cause some of this to flow into the well. 

In conclusion, then, any source of supply may be contami- 
nated, and there is danger in the use of well waters especially 
in crowded districts. Numerous diseases are distributed by 
impure waters, and in any case of an epidemic of these dis- 
eases that are propagated by germs, the water supply should 
be very carefully examined, and it is always advisable at 
such times to boil the water before using. 



CHAPTER VI 

PURIFICATION OF WATER SUPPLIES 

Water is naturally purified by sedimentation, dilution, 
oxidation, filtration, vegetable growth, and bacterial action. 
The extent to which each of these agencies improves the 
water depends on a variety of circumstances. With the 
deposit of mud and silt there is often carried down a large 
amount of organic matter ; indeed, the presence of a certain 
amount of suspended matter in some of the Western rivers 
seems to assist in the removal of organic impurities. Sedi- 
mentation alone, however, will not purify an unsafe water. 

Dilution of a small stream carrying sewage by a large 
stream of purer water seems to make it of better quality, 
but really the organic matter is simply distributed through 
a larger volume of water, and not necessarily destroyed. 

Oxidation, by a rapid fall, or by exposure to the air in 
running over riffles, as in a shallow stream, has been 
depended upon formerly for a large amount of purification. 
There is a difference of opinion, however, as to the extent 
to which oxidation will destroy pathogenic germs, but it 
usually happens that these conditions are very favorable to 
purification. W. C. Young 1 states, as the result of his 
experiments, that the removal of dissolved organic matter 
from river water by natural means is extremely slow. The 
principal agent in this purification is the growth of vegeta- 
ble organisms, and atmospheric oxidation has little effect. 

1 Jour. Soc. Chem. Ind., Vol. 13, p. 318. 
79 



80 SANITARY AND APPLIED CHEMISTRY 

FILTRATION AND SOFTENING 

Water may be further purified by some artificial method 
of filtration, and this may be done on a large scale by a 
public water supply company in a much more economical 
and efficient manner than by household filtration. 

For the filtration of public water supplies, some of the 
most efficient means have been found to be, — 

1. Slow sand filtration. 

2. Mechanical filtration. 

3. The iron process. 

4. Clark's process. 

In the slow sand filtration system, the water is run con- 
tinuously on to a filter made of coarse gravel, fine gravel, 
and sand, suitably underdrained. When a filter begins to 
clog, its surface is cleaned by paring off a fraction of an inch 
of sand. In the use of the filter it has been found that its 
efficiency increases for some time after it is first installed, 
as the mat or slime of bacteria and organic matter increases. 
The top layer, however, does not do all the work of filtra- 
tion, as was shown by Eiensch in the case of the Altona 
filters. He found that the unfiltered water contained 36,320 
microbes per cubic centimeter, and after passing through 
the upper or slime layer of the filter it contained 1876 mi- 
crobes, and finally the effluent contained only 44 microbes 
per cubic centimeter. 

For the proper working of this system quite a large area 
of filter beds is required, as it must be so arranged that 
some beds can be cleaned while others are in use. The area 
of the beds in Hudson, New York, for instance, is 30,000 sq. 
ft. An average rate of filtration of about three million gal- 
lons per acre per 24 hours is usually attained. 

As to the efficiency of this system of filtration, attention 
may be called again to the Altona case, where ten of these 



PURIFICATION OF WATER SUPPLIES 81 

filters are used. The average number of germs in the unfil- 
tered water was 28,667 and in the filtered water only 90 ; 
so 99.69% of the germs were removed. The removal of the 
bacteria is not due simply to straining, but the conditions 
within the filter are unfavorable to the life of the bacteria. 
The food material for bacterial growth is gradually taken 
away, and the water actually improves in quality as it flows 
through the pipes to the consumer. In Lawrence, Massa- 
chusetts, it is stated that the mortality from typhoid fever 
has been reduced 40% since this system of filtration was 
introduced. 

In order to avoid the great expense of erecting filtering 
basins, filtration galleries are sometimes built beneath the 
surface along the banks of a stream, and so arranged that the 
water that percolates through the sand into the gallery can 
be pumped into the service pipes. These galleries, however, 
are not easily inspected and are liable to get out of repair or 
become clogged. 

Mechanical filtration may be performed either with or 
without the use of alum or some other coagulant. Here 
the water is forced through a bed of sand contained in a 
tank, and after the filter becomes' clogged it can be cleaned 
in about fifteen minutes by reversing the current of water. 
It is interesting to notice that in this process the " bacterial 
jelly" on the top of the filter beds is replaced by an artificial 
inorganic jelly of aluminum hydroxid, which entangles the 
bacteria and at the same time reduces the amount of organic 
matter in the water. The use of alum is applicable only to 
those waters possessing temporary hardness. In that case 
the calcium bicarbonate will cause the precipitation of the 
aluminum hydroxid. 

Experiment 53. The action of a coagulant may be 
illustrated by putting a few grams of alum into a sample of 



82 SANITARY AND APPLIED CHEMISTRY 

water, and adding to it enough of a tincture of cochineal 
to give it a strong red color. Add to this ammonium 
hydroxid in excess, and allow to stand for some time, 
when the coloring matter will be precipitated with the 
aluminum hydroxid, Al(OH) 3 , leaving the solution colorless. 

In the iron process the water is brought in contact with 
spongy iron, and the result is the precipitation of ferric 
hydroxid, which carries down with it most of the organic 
matter. The precipitate may be removed either by sedi- 
mentation or by filtration through sand. 

In the Anderson process ferric hydrate is formed in the 
water by the combined action of iron scraps and air, and 
the precipitate is filtered out. 

Experiment 54. To a dilute solution of ferric chlorid, 
add an excess of ammonium hydroxid. The reddish brown 
precipitate of ferric hydroxid produced is similar to that in 
the iron process. 

Clark's process for softening water depends on the pre- 
cipitation of a large part of the carbonates by the addition 
of calcium hydroxid (limewater) in accordance with the 
reaction CaH 2 (C0 3 ) 2 + Ca (OH), = 2 CaC0 3 + 2 H 2 0. The 
precipitate of calcium carbonate is then allowed to settle, or 
is filtered off. (See p. 67, also Soap.) A large proportion 
of the organic matter is carried down with this precipitate. 

Experiment 54 a. Pass a current of carbon dioxid through 
a dilute solution of calcium chlorid till the precipitate at 
first formed is dissolved. Add to this solution an excess of 
limewater and notice the formation of the precipitate. 

Where household filtration is a necessity, some device of 
porous stone or tile, sand or animal charcoal, may be used. 
The filter should be of such construction that if of stone 
it can be readily cleaned with hot water and a stiff brush, 
or by thoroughly washing if of sand or similar material. 



PURIFICATION OF WATER SUPPLIES 83 

The Pasteur-Chamberland filter, which is made of unglazed 
porcelain, is one of the most efficient filters, as bacteria are 
practically removed from the water by its use. The Worms, 
or Fisher, filter, made by the use of plates of artificial stone, 
has also proved efficient. It is of importance to remember 
that waters that are bad from the presence of organic matter 
may be made safe by thoroughly boiling, and also by distil- 
lation, and condensation of the steam. 

Ground water should be stored in dark reservoirs, as 
under these conditions the algae and other troublesome or- 
ganisms, which injure the water, do not develop as rapidly. 
Surface water often improves in quality when stored in 
clean open reservoirs where the sides have been thoroughly 
cleared of vegetation. The effect of mud deposits in storage 
reservoirs is not necessarily harmful. If, however, these 
deposits furnish food for and encourage the growth of organ- 
isms that by their development impart a disagreeable taste 
and odor to the water, they should be removed. 

The good effect of freezing has been very much over- 
estimated, according to Prudden. 1 Clear, transparent ice, 
from the surface of an open body of water, when melted, 
yields about 10% as many bacteria as were present in the 
original water. If a pond freezes solid to the bottom, all 
the impurities that were in the water will be in the ice. 

1 Medical Becord, March 26, 1887. 



CHAPTER VII 
SEWAGE DISPOSAL 

The only practical methods that have been proposed for 
the disposal of the " wastes of animal life " are the " dry- 
earth" system and the "water carriage" system. The 
former may be utilized in detached houses where no better 
method is available. The water carriage system is prefer- 
able, both from the standpoint of economy and that of 
sanitary efficiency. 

The organic material that accumulates in the waste of 
modern dwellings is of such a character that it must be very 
quickly removed or it will prove a menace to health. 
Sewage may be defined as " a complex mixture, with water, 
of the waste products of life and industry from densely 
settled communities." The only solids of importance which 
this sewage carries are those which are susceptible of solu- 
tion in water, or which become disintegrated in transit. 
Sewage consists very largely of water which acts as a 
vehicle to carry away a small quantity of other substances. 
In 1000 parts of sewage it is estimated that there is 1 part 
of mineral matter and 1 part of organic matter, leaving 
998 parts of pure water. Now, the mineral matter con- 
tained in sewage is practically of no importance, so that all 
our efforts are directed toward the removal of the 1 part of 
organic matter in 1000 parts of water. The only really 
dangerous substances in sewage are the disease-producing 
organisms, but the gases given off as the result of decompo- 
sition are extremely disagreeable. Sewer gas is not as liable 

84 



SEWAGE DISPOSAL 85 

to contain microorganisms, which, will be injurious to the 
health, as was formerly supposed. 

The material which issues from the sewers of large cities 
contains no dissolved oxygen and no oxidized nitrogen. 
The reason for this is that the available oxygen of the water 
has been removed in oxidizing a portion of the carbon of 
the organic matter, but it has not sufficed, also, for the 
oxidation of the nitrogen, and further oxidation can go on 
only by the addition of more oxygen to the water. If the 
nitrogenous material in the sewers is represented by ammo- 
nia, then the following equation may be written : — 

2 NH 3 + 4 2 = 2 HN0 3 + 2 H 2 0. 

Now this nitric acid, coming in contact with the calcium 
carbonate of the soil and of the water is decomposed 
thus : — 

CaC0 3 + 2 HNO3 = Ca(N0 3 ) 2 + H 2 + C0 2 . 

The most modern theory for the purification of sewage is 
that it is carried on very largely by bacteria, and even this 
process of nitrification, as it is called, which the above equa- 
tion represents, cannot go on without the intervention of 
nitrifying bacteria, and this class of organisms must work 
in a medium containing a sufficient quantity of free oxygen. 
This purification may take place in water, when there is a 
sufficient quantity of the free oxygen in proportion to the 
filth handled. In soil this nitrification is of the utmost im- 
portance in the process of preparing it for the growth of 
plants, and in keeping up its fertility. 

DISPOSAL OP SEWAGE BY DILUTION 

If the stream into which the sewage is poured is small, 
and the current of low velocity, the result will be the pro- 
duction of a very disagreeable odor from the decomposition 



86 SANITARY AND APPLIED CHEMISTRY 

of the sewage, but, if, on the other hand, the flow of the 
stream is large, this sewage will be distributed through so 
much water that we shall not find any offensive odor arising 
from it. It has been estimated that a stream which carries 
off sewage should have a volume of from twenty-five to 
thirty-five times that of the sewage ; the proportion, how- 
ever, depends on the amount of free oxygen that is carried 
by the stream and several other factors. The amount of 
water needed to carry off the sewage can be calculated 
readily, by knowing the amount of water supplied to the 
town, as it has been found under normal conditions, that 
the volume of sewage is practically the same as the amount 
of water supplied. 

In the case of the city of Milwaukee, as an illustration, 
for many years the sewage was turned into the Milwaukee 
River, a small stream, which became extremely foul, but 
arrangements were made to pump a large amount of water 
from the lake into the river 3^- miles inland, thus supplying 
26 times as much water as the volume of the sewage, and 
by so doing the sewage was flushed out with the water, 
and the odor disappeared. To handle the sewage of Chicago 
it would be necessary to follow the same plan, and have 25 
times as much water in the drainage canal as the sewage 
of the city. 

The objection to the disposal of sewage in this way 
is, of course, the rendering of a river water so impure. 
Although some experimenters have shown that water after 
running 20 miles is quite completely purified by the process 
of oxidation and nitrification, others claim that even by run- 
ning ten times as far, the pathogenic germs would not be re- 
moved, and there is a natural repugnance against using, for 
drinking purposes, water that has been at any time contami- 
nated by sewage. 



SEWAGE DISPOSAL 87 

DISPOSAL OP SEWAGE BY IRRIGATION 

Another method for disposal of sewage is by irrigation. 
It is well known that there is a large amount of available 
fertilizing material in the sewage of the modern city ; for 
instance, the sewage of London is said to be worth annually 
$14,000,000 for fertilizing purposes. Some hold that sewage 
is not of such great intrinsic value after all, for it has been 
practically found that it is not possible to handle very large 
quantities of sewage upon a farm, and that the process 
cannot be applied upon a very large scale. Another disad- 
vantage is that when there is a large amount of rain, or 
when the water freezes, the process is very much interfered 
with, and the system to be satisfactory must be carried on 
without any interruption day after day, so as not to allow 
any offensive matter to collect. The late Colonel Waring 1 
states that an acre of land will be required to care for the 
sewage of from 250 to 500 persons, and when the question of 
growing crops is of secondary importance, and the soil is 
porous and sandy, the sewage of 1000 to 1500 can be purified 
on an acre of ground. The city of Berlin has set aside 
20,000 acres for a sewage farm, and it is said that it actually 
receives a yearly profit of $60,000 from the operation. 

INTERMITTENT FILTRATION 

The next method for disposal of sewage is by intermittent 
nitration. This process is a natural one, because it depends 
for its success upon the prevalence of certain natural con- 
ditions; that is, the presence of oxygen and living micro- 
organisms. If we allow sewage to run, for some time,, upon 
a filter bed composed of sand and gravel and then turn this 
sewage on to another filter bed and allow the water to run 
out of the first bed and the air to enter the spaces between the 

1 Harrington, " Practical Hygiene," p. 496. 



88 SANITARY AND APPLIED CHEMISTRY 

grains of sand, we furnish the means for the growth of the 
microorganisms. This is much more satisfactory than at- 
tempting to filter continuously through the same filter bed- 
As an illustration it was shown in one case that by the use 
of this process where 31,400 gal. of sewage per acre was fil- 
tered, 98.6% of the organic impurity was removed, and 99% 
of the bacteria. 

THE SEPTIC TANK 

There is a modification of the above method which is 
known as the use of the septic tank, in which the sewage is 
liquefied by being stored first in the sunshine or in the air, 
allowing the aerobic bacteria to work, and afterward in a 
closed tank where another class of bacteria (the anaerobic) 
carry on their purifying process. This material is then run 
upon filter beds, and a very pure effluent is the result. Some 
engineers prefer to run the sewage first into a closed tank, 
through which it requires from 12 to 24 hours to pass, and 
where a thick scum covers the surface, gases are given off, 
and very complete decomposition takes place. The effluent 
from this tank is then run on to filter beds. It is to be noted 
that both aerobic bacteria, or those which work in light and 
air, and anaerobic bacteria assist in the purification of sewage. 

PRECIPITATION OF SEWAGE 

Another method for sewage disposal is by chemical pre- 
cipitation. For this purpose such substances as ferrous 
sulfate, ferric sulfate, lime, or alum are used. It was 
at first proposed to utilize the precipitated material as a 
fertilizer, and considerable money has been spent in pre- 
paring this material and extracting the water from it by 
pressure. This process, however, has not been found to be 
very satisfactory, and improvements must be carried still 
farther before this method for disposal of sewage will be 
extensively adopted. 



SEWAGE DISPOSAL 89 

To recapitulate, for the purification of sewage, we must 
depend largely upon the work of bacteria often in the pres- 
ence of oxygen, and any plan which utilizes the work of 
these organisms to the greatest extent, and furnishes the 
most complete conditions, for work in this way, will be 
successful. 

DISPOSAL OF HOUSEHOLD WASTE 

A method for disposing of garbage or household waste 
economically has long perplexed the health authorities. 
Two conditions may be considered : that of disposing of it 
on the premises where it is produced, and that by the city 
authorities. 

Several methods have been used for disposal of refuse 
without removal from the premises. Among these the pro- 
cess of burning in the stove, range, or furnace, either with 
or without previous drying is suggested. This is efficient 
and practical if the amount of such waste material is not 
too large, and if a good fire is maintained. In summer, 
when there is naturally a larger amount of refuse, and the 
fires are not kept burning so continuously, it is often 
difficult to handle garbage in this way. 

A modification of the above method consists in having an 
enlargement of the smoke pipe of the stove at the elbow, 
and to introduce into this, through an opening in the side, a 
perforated basket containing the garbage. The material 
soon becomes dry and is partially charred, and then may 
be taken out and put into the stove, where it is useful 
as fuel. 

In some cities the plan of building brick or stone furnaces 
in the yard, for the sole purpose of burning rubbish, has 
been adopted with great success. 

Another method of disposal is by burying in the soil, and 
as the decomposition takes place rapidly, if only a few 



90 SANITARY AND APPLIED CHEMISTRY 

inches of soil is placed over the material, no obnoxious odor 
arises to contaminate the air. When one hole is filled, it is 
covered and another is dug beside it ; but these holes must 
not be too deep or too large. 

If the city or village undertakes to dispose of the gar- 
bage, usually great expense is incurred, as the quantity is 
very large. For instance, in Manhattan alone the dry refuse 
amounts to 1,000,000 tons in a year, and the garbage is 
175,000 tons per year. 1 

Disposing of garbage to farmers for feeding of stock or 
swine is also practical. This involves a long haul of ill- 
smelling material through the streets, and is particularly 
objectionable if the material is not collected every day. 

In some localities garbage is loaded on to scows, towed 
out to sea and dumped, but here the incoming tide may 
throw the decomposing material back on the shore. 

There is a very valid objection to using such refuse, 
even if the more perishable material is excluded, for filling 
in the so-called " made land," as decomposition will continue 
for years in this soil, and the air of dwellings built upon 
it will be contaminated. 

Cremation has been adopted in many cities with good suc- 
cess. In 1899, 81 communities in Great Britain were em- 
ploying incineration as the chief means for disposal of 
refuse, and 76 of them turned the developed heat from the 
combustion of this refuse to some useful purpose, such as 
making steam to run electric lighting plants, for sewage 
pumping works, for grinding road material, and for use in 
the process of disinfection of clothing. 2 

Another plan is by " reduction," in which method the gar- 
bage is dried in steam-jacketed cylinders, the dried residue 
then extracted with naphtha, and the grease thus removed is 

1 Price, " Handbook on Sanitation," p. 49. 

2 Harrington, " Practical Hygiene," p. 509. 



SEWAGE DISPOSAL 91 

saved as a valuable product. The residue is again dried and 
worked up into a fertilizer. It is well to remember that 
such quickly decomposing material as garbage should be 
immediately removed under sanitary inspection, whether 
any financial profit comes to the city from its treatment 
or otherwise. 



CHAPTER VIII 
CLEANING: SOAP, BLUING 

With our modern knowledge of the means of transmitting 
disease, filth is something to be avoided, as it assists in the 
spread of infection from one locality to another. The love 
of cleanliness, which is considered a sign of a higher civili- 
zation, is, no doubt, the outgrowth of years of experience 
with the dangers of dirt. This abhorrence for filth is a 
sanitary safeguard: it protects the body, the air, the water 
supply, and the food supply. As man has advanced he has 
demanded some cleansing agent for the body, the utensils, 
and the clothing, and so a great industry has developed for 
the preparation of these agents. 

Substances used for cleaning act either mechanically or 
chemically to remove the offensive materials. In the use of 
soap and sand, for scouring, there is a combination of these 
methods ; and, in fact, when the chemical loosens up the 
fibers or sets free the dirt, some mechanical process is 
often required to remove it. 

Most of the polishing and cleaning powders on the market 
depend, for their efficiency, upon the action of a very finely 
divided substance like silica, precipitated chalk, or rouge. 
This is mixed with some fat or oil; thus, some "Putz Pom- 
ades" contain rouge, some finely divided silica, and a per- 
fumed fat. In the choice of a polishing material, one should 
be selected that is so finely divided that it will not scratch 
the metal. Dry sodium bicarbonate (baking soda) can be 
safely used for cleaning and polishing. 

92 



CLEANING : SOAP, BLUING 93 

Borax, Na 2 B 4 7 , added to water, greatly aids in the removal 
of dirt, in special cases. Ammonium hydroxid (aqua am- 
monia) is also used for the same purpose, and as it forms a 
soap with the oily matters of the skin or of the fabrics 
washed, it is a convenient cleaning agent. A teaspoonful of 
ammonia to a quart of water is an excellent wash for wood 
work, and may be used to brighten carpets or rugs. Much 
of the "household ammonia " on the market is of a very low 
grade, and so it is always advisable to purchase ammonia 
from a druggist. 

A cleaning material should not only remove the grease or 
dirt, but it must be of such a nature that it will not injure 
the article cleaned. From the recent work of Mrs. Rich- 
ards, 1 many of the following suggestions are taken. 

In some cases, as with wood, leather, metal, etc., the 
dirt does not penetrate into the interior, but remains 
on the surface; in other cases the whole fabric is filled with 
dust and grease. All polished wood surfaces, except those 
finished with wax, may be cleaned with a weak solution of 
ammonia, or soap, but they should never be treated with 
a strong alkali. 

As solvents for grease, either kerosene or turpentine may 
be used, and should be applied with a soft cloth. Painted 
surfaces, especially if white, may be cleaned with a little 
" whiting," CaC0 3 , which can be applied with a piece of 
cheese cloth. The wood is afterward washed with water 
and wiped dry. Painted walls if painted with oil paints 
can be cleaned in the same way, but " tinted" walls, since 
water colors are used, are disfigured by this treatment. 

Leather may be kept bright and clean by the use of 
kerosene, or occasionally a little oil. Marble may be 
scoured with sand soap, and finally polished with a coarse 
flannel. It should not be forgotten that marble is calcium 

1 Richards and Elliott, " The Chemistry of Cooking and Cleaning." 



94 SANITARY AND APPLIED CHEMISTRY 

carbonate, CaC0 3 , and consequently should never be treated 
with an acid, or even an acid fruit juice. Metals can usually 
be cleaned with a hot alkaline solution or a little kerosene. 
To clean glass, it may be covered with a paste of whiting, 
ammonia, and water, and after it is dry this may be rubbed 
off with a woolen cloth or with paper. Kerosene is excellent 
for this purpose, especially in the winter when the water 
would freeze. 

Household fabrics are often washed with alkaline solu- 
tions or with soap. In some cases naphtha may be used 
for washing such fabrics. As some of the solvents, such as 
naphtha, benzine, turpentine, and gasoline are frequently 
used for cleaning, and removing grease, it is extremely 
important to remember that they are all very volatile, and 
that the vapors may take fire from a lamp, gas jet or 
stove, even if at some distance. On this account work of 
this kind should be done by daylight and out of doors, if 
possible. Many serious burns occur from lack of these 
precautions. 

In the use of the volatile solvents like gasoline, enough 
should be used to cover a large portion of the goods, and 
if possible afterwards wash thoroughly with water. 

To remove stains, spots, and tarnish, a little knowledge of 
chemistry will serve an excellent purpose. Since grease is 
readily absorbed by blotting paper, spots may often be re- 
moved from fabrics by placing the goods between two pieces 
of blotting paper, and then heating with a warm iron. 
French chalk will sometimes absorb the grease, especially if 
the spots are fresh. Grease may also be removed by the 
use of hot water and soap, ammonia, or even borax. If 
there is danger that these solvents will injure the goods 
or the colors, it is better to use some solvent such as 
chloroform, ether, alcohol, turpentine, benzine, or naphtha. 
Ether and chloroform are better adapted to the more delicate 



CLEANING: SOAP, BLUING 95 

fabrics. "The troublesome ( dust spot ' has usually a neg- 
lected grease spot for its foundation. After the grease is 
dissolved the dust must be cleaned out by thorough rinsing 
with fresh liquid or by brushing after the spot is dry." 1 

Since paints consist of oil and some coloring matter and 
lead or zinc oxides, paint spots should be treated with a sol- 
vent for the oil, and then the coloring matter can be brushed 
off. Fresh spots may be treated with turpentine, benzine, 
naphtha, or gasoline, but old paint spots must be softened 
with oil or grease, and may then be removed by the appro- 
priate solvent. Pitch, tar, or varnish may be treated with 
oil, and then be dissolved out with turpentine. 

Sugar deposits are soluble in warm water. If acids have 
destroyed the color of goods, this may usually be restored 
by ammonia, and dilute alcohol may be used in the same 
way for the stains from fruit. 

Ink spots would not be so difficult to remove if we knew 
in advance the composition of the ink. Fresh ink usually 
dissolves in cold water, though sometimes sour milk is more 
efficient. Ink stains may also be removed with blotting paper 
or some absorbent. Ink stains on marble may be treated 
with turpentine, baking soda, or strong alkalies, or a paste 
may be made with the alkali and turpentine, and this may 
be left for some time in contact with the spot, and finally 
washed off with water. A dilute solution of oxalic acid may 
often be successfully used to remove either ink stains or iron- 
rust spots. 

If there is much iron in the water supply, this may be 
removed from bowls or other porcelain ware by the use of 
hydrochloric acid, then rinse with water, and finally with a 
solution of soda. 

Silver is readily tarnished by sulfur, either from eggs, 
or from rubber bands or elastic, or sometimes from the 

1 Richards and Elliott, loc. cit. 



96 SANITARY AND APPLIED CHEMISTRY 

sulfur compounds in the illuminating gas. The sulfid of 
silver thus formed is grayish to black. Silver thus tarnished 
should be rubbed with moist common salt before washing, 
thus forming a silver chlorid, which is then washed in am- 
monia, in which it is soluble. 

For cleaning and polishing brass and copper, nothing is 
better than oil and rotten-stone, and most of the good pol- 
ishes on the market are made from these materials, with al- 
cohol, turpentine, or soap. Kerosene is useful in keeping 
metals bright, as well as glass and wood. Aluminum 
may be cleaned by the use of whiting or any silver polish, 
but alkalies should not be used upon this metal. Aluminum 
does not readily tarnish. As it does not rust, with ordinary 
care it will, in a kitchen utensil, last for many years. 

Experiment 55. To remove an iron-rust spot from a piece 
of goods, stretch the cloth over a dish containing hot water, 
then as the steam arises and the goods become moist, drop 
a little muriatic acid, HC1, upon the rust spot with a medi- 
cine dropper ; after a moment lower it into the water. If 
the spot is not removed, repeat the operation, then rinse in 
clear water, and finally in a dilute solution of ammonia to 
neutralize any acid that might remain and injure the goods. 1 

Iron-rust stains may often be completely removed from 
delicate fabrics by the use of lemon juice and common 
salt. 

SOAP 

Water, and a few other solvents, are used to remove dirt, 
or, as it is sometimes called, "matter out of place." Some 
of these foreign substances readily dissolve in the water ; 
others, like the fats, will dissolve in ether or gasoline; and 
still others, as the resins, will dissolve in alcohol. Some 
form of alkali, such as wood ashes, was formerly used with 

1 Richards and Elliott. 



CLEANING: SOAP, BLUING 97 

the water, to assist in removing the dirt. It was found, 
however, that this had a very destructive action on the goods, 
so a " saponified" fat, the product produced by the action of 
an alkali on a fat, or what we call soap, came into use. 
This, when well made, does not injure the goods. Soap was 
used instead of the lye from the lixiviation of ashes, long 
before the chemistry of the process became known. It was 
not till 1813 that Chevreul published his scientific researches 
on the composition of fats and the process of soap-making. 
The raw materials used in soap manufacture are an alkali 
known as " caustic alkali," which may be either sodium hy- 
droxid (NaOH), which makes a hard soap, or potassium 
hydroxid (KOH), which makes a soft soap. These are 
made by boiling the carbonate with slaked lime, in accord- 
ance with the equation: — 

Na 2 C0 3 +Ca(OH) 2 =CaC0 3 +2 NaOH. 

From this mixture the calcium carbonate settles out, and 
the solution of the caustic alkali is boiled down to a solid, 
and is put upon the market under the name of "concentrated 
lye," or the concentrated solution is used directly by the 
soap maker. 

More recently caustic soda has been made directly by the 
electrolysis of sodium chlorid, NaCl. The sodium deposited 
at one pole is dissolved in water, and the chlorin is used for 
making bleaching powder. 

The second ingredient of a soap is either a vegetable or 
animal fat or oil or a resin. Such oils as that of palm nut, 
cocoanut, olive, hemp seed, linseed, cotton seed, fish, or lard 
may be used, and fats like beef tallow, mutton tallow, lard, 
or house grease. . 

The process of " saponification" may be brought about 
either by the action of water or steam at high temperature 
and pressure (especially in the presence of a dilute mineral 



98 SANITARY AND APPLIED CHEMISTRY 

acid), by the action of caustic alkalies, or sometimes by the 
use of lime (see Candles, p. 49). 

The fats may be briefly described as consisting of ethers 
of the triatomic alcohol-radicle, containing glycyl, C 3 H 5 . By 
treatment with alkalies or high-pressure steam, they yield 
gylcyl alcohol (glycerin) and stearic or other fatty acid. 1 

The name given to the compound of the acid and 
glycerin is stearin, palmitin, or olein. In the case of 
stearin, the saponification equation would be: — 

C 8 H 5 (C u H850 2 )s + 3 KOH = C 3 H 5 (OH) 3 + 3 KC^O* 

Stearin Caustic Potash Glycerin Soap 

With palmitin or olein, the reaction is similar. If the 
fat or oil is solid, it contains a preponderance of stearin or 
palmitin, but if liquid, there is an excess of olein. 

In making soap on a large scale, 2 a kettle, provided with 
both a closed and open steam coil, so that the soap may be 
boiled either by the heat or the free steam, is used. A ket- 
tle that will hold 100,000 lb. of soap is 15 ft. in di- 
ameter and 21 ft. high, and is made of -|-in. boiler plate. 
The melted fat and lye are run into the kettle and mixed 
by the aid of free steam and boiled for some time, or until 
the soap has a dry, firm feel between the fingers ; it is then 
" salted out " by adding common salt. In boiling, the saponi- 
fication represented in the above equation has taken place, 
and when salt is added this causes the soap to separate from 
the caustic lye and glycerin. After boiling, to mix thor- 
oughly, the mass is allowed to stand in the kettle till the 
soap rises to the top, and then the lye may be drawn off at 
the bottom of the kettle. Some more strong lye is then 
added, and the boiling is continued till the material is 
fully saponified, which the experienced soap boiler knows 

1 Allen, " Commercial Organic Analysis," p. 183. 

2 Thorp, "Outlines of Industrial Chemistry,' ' p. 340. 



CLEANING: SOAP, BLUING 99 

by sight, feel, and taste, and then the contents of the 
kettle is again allowed to stand for a while, and the addi- 
tional lye is drawn off. The soap is then boiled with some 
water, and is allowed to settle again, to allow the separation 
of more alkali, dirt and impurities, called "nigre." After 
standing several days, the soap is pumped into the 
"crutcher," which consists of a broad, vertical screw work- 
ing within a cylinder, which is placed in a larger tank. 
Here it is thoroughly mixed, and any perfume or scouring 
material may be added. The soap is then drawn off into 
rectangular "frames/' holding about 1000 lb., where it is 
allowed to solidify. The sides of these frames are re- 
moved and the soap is cut, by means of a wire, into slabs 
and then into bars. If put on the market in the form of 
cakes, the bars are pressed into the desired shape. 

For making white soaps, tallow, palm oil, and cocoanut 
oil are used. Castile soap, if genuine, is made from olive oil, 
sometimes with the addition of cocoanut or rape seed oil. 
It is useless to attempt to make a good soap out of inferior 
material. In making lower grades of soap, cheaper fats are 
used, and frequently those that have a rancid odor. This is 
sometimes "corrected" by the addition of a strong perfume, 
like oil of "mirbane," — nitrobenzene, made from coal tar. 
Yellow soaps almost always contain considerable rosin; that 
is, they are made by the usual process, except that quite a 
large proportion of rosin is used to replace the fat. This 
has valuable soap-making qualities, and would not be classi- 
fied as an adulterant of soap. Cocoanut oil saponifies with- 
out boiling, so it is used in making the "cold process" soap. 
This material also admits of the use of a larger quantity of 
water, so that the soap will be hard and still contain as 
much as 70 % of water. Soap is mottled by stirring into 
it, while warm, some coloring substance, such as copperas, 
ultramarine, or an aniline color. 



100 SANITARY AND APPLIED CHEMISTRY 

Sand soap, pumice soap, and compounds of a similar 
character are made by incorporating sand or powdered pum- 
ice, with the ground soap, and this ought to lessen the 
price of the soap very materially. These substances can act 
only mechanically; that is, they sandpaper off the dirt. A 
silicated soap is made by mixing with the ordinary soap 
some silicate of soda or soluble glass, as it is called. Into 
most laundry soaps both sodium silicate and sodium car- 
bonate are " crutched," as a filler to soften hard water and 
to give additional detergent properties. 

Toilet soap is made either by melting raw soap, by per- 
fuming an odorless soap, after cutting in fine shavings and 
drying, or by making the soap directly by the use of pure 
, materials. In either case the mass is colored by metallic 
oxides or aniline colors, and is perfumed by the use of 
essential oils, and then it is pressed into molds while 
yet fresh. 

To make a transparent soap it is necessary to dissolve an 
ordinary soap in alcohol, allow the insoluble residue to 
settle out, and distill the alcoholic solution to jelly. This 
may then be pressed into molds and dried. Another 
method very frequently employed is to make a cold process 
soap, with coloring matter and perfume added, and then to 
add to the mass more glycerin, or a strong sugar solution, 
which renders it still more transparent. 

Soft soap is made directly by the use of potash lye, or by 
the use of soda lye and considerable water. The glycerin 
and the excess of lye, if any, remain in the soft soap. This 
is used in "fulling" or shrinking cloth and in other manu- 
facturing operations, probably on account of the excess 
of alkali which it contains. 

The salt lye which is drawn off from the kettle in which 
soap is boiled is used for the manufacture of glycerin. In 
this process the soluble soap and impurities are taken out 



CLEANING : SOAP, BLUING 101 

by chemical treatment, and mineral salts are separated 
by evaporation and crystallization. The purified crude 
residue containing about 80 % glycerin is distilled with 
steam under diminished pressure. 

It is not economy to use a cheap soap, as on account of 
the excess of alkali which it usually contains it injures the 
fabrics washed, by causing the fibers to disintegrate and 
readily fall apart. 

There is a great advantage in using a well-dried soap, 
as it does not so readily become soft in the water and there- 
fore does not wash away so quickly. A laundry soap 
will lose 25 % of water if the bars are piled and allowed 
to remain for some time where they are freely exposed to 
the air. 

In his researches on soap, Chevreul said that the cleaning 
action was because the soap was decomposed, when brought 
in contact with water, into fatty acid and alkali. The 
impurities are set free by the alkali and entangled by the 
fat acid salts, and thus removed with the lather. Thus it 
will be seen that vigorous rubbing is not necessary to remove 
the dirt, though, of course, it aids the process. 

Ordinary soaps are readily soluble in water, but if the 
water is " hard w from the presence of lime or similar 
mineral substances, the alkali soap is decomposed and an 
insoluble lime soap is precipitated, thus forming a dis- 
agreeable scum on the water. Not until all this lime is 
thrown down by the soap will the latter begin to have a 
detergent action. 

The equation for the formation of the lime soap would 
be: — 

2C,AAHa + CaS0 4 = Ca(C 18 H, 5 2 ) 2 + Na,S0 4 . 

On account of the necessity for using hard water in some 
localities "washing soda" Na 2 C0 3 + 10 H 2 is used to 



102 SANITARY AND APPLIED CHEMISTRY 

"break" the water; that is, to precipitate the lime so that 
less soap will be required, thus : — 

CaH 2 (C0 3 ) 2 + Na 2 C0 3 = CaC0 3 + 2NaHC0 3 . 

(See Hard water, p. 67.) 

In order to make a laundry soap fit for hard water, sodium 
carbonate is added to it in the crutching. 

Experiment 56. To make a hard soap, dissolve in a 
medium-sized beaker 15 grams of caustic soda (sticks) in 
120 cc. of water, and pour one half of this into a porcelain 
evaporating dish of at least 500 cc. capacity, add 60 cc. of 
water and 50 grams of tallow. Boil this solution for three 
quarters of an hour, carefully replacing, from time to time, 
the water that has been lost by evaporation; then add the 
remainder of the solution of caustic soda and boil for at 
least an hour more. Water should be added as before, but 
the volume of the liquid may be allowed to decrease about 
one third. Add 20 grams of salt, boil for a few minutes, 
and allow the liquid to cool. The soap will rise to the top, 
and the glycerin, excess of lye, and salt will remain in 
solution. 

Experiment 57. Slightly acidify the water solution sepa- 
rated from the soap in the above experiment with dilute 
hydrochloric acid. If any fatty acids or impurities separate 
out, filter. Pour the solution into a porcelain evaporating 
dish, and evaporate to dryness on a water bath. Dissolve 
the residue in strong alcohol, filter or decant from the un- 
dissolved crystals of salt, and evaporate the alcohol. The 
slight residue will be sticky, and give the sweet taste of 
glycerin. 

Experiment 58. Cut a good quality of soap into shavings 
and mix with hot water on a water bath, until well dissolved. 
Add dilute sulfuric acid until the solution is acid. Note 



CLEANING: SOAP, BLUING 103 

that if the soap is " filled/' the sodium carbonate will cause 
an effervescence on adding acid. Heat on the water bath for 
some time or boil slowly, and the fatty acid will separate, 
forming an oily layer on the top. When clear this may be 
separated from the water by pouring on a wet filter, and the 
sulfuric acid removed by washing on the filter with hot water. 
Washing soda, 3sra 2 CO 3 10 H 2 0, is often used, not only 
to soften hard water, but as a stronger washing agent 
than soap. This is a much better material than most of the 
so-called washing powders of the grocer. It should always 
be dissolved in a bottle or other vessel, and used as a solu- 
tion in the quantities necessary. An excess disintegrates 
the fabrics, or " rots "the goods. Sometimes the washing 
powders or liquids on the market contain in addition to the 
washing soda, a little soap or ammonium carbonate or a 
small per cent of borax, but they are much more expensive 
than the common washing soda, and no more efficient. 

Experiment 59. To test a washing powder for sodium car- 
bonate, put a little of it in a test tube and add a few drops 
of hydrochloric acid. If there is a brisk effervescence, it 
will indicate the presence of a carbonate, and if the gas that 
is given off colors the flame of a Bunsen burner yellow, it 
indicates sodium. 

BLUING* 

Bluing is the process resorted to in the laundry to over- 
come the slight yellow color of the clothes, and for the 
same purpose in the bleacheries where new goods are finished. 

Indigo was one of the substances most commonly used 
some years ago. It was known to the ancient Egyptians as 
a dye and to the Bomans as a pigment. The method of 
using it for bluing, as it is insoluble in water, is to tie up 
a lump in a cloth, and when soaked in water the finely 
divided precipitate which is in suspension will give a blue 



104 SANITARY AND APPLIED CHEMISTRY 

color to the water, and to the clothes, which are immersed 
in it. 

Prussian blue (ferric ferrocyanid), Fe 4 (Fe(CN) 6 ) 3 , is also 
used for bluing. It is insoluble in water and in mineral 
acids, but is decomposed by alkalies and dissolved by oxalic 
acid. It is generally used as a solution or " liquid blue," but 
this imparts to the goods a greenish blue color. On account 
of the ease with which it is decomposed by alkalies, there 
is danger that " iron rust " will be deposited on the goods 
if this form of blue is used. 

Experiment 60. Make Prussian blue by the action of 
ferric chlorid, FeCl 3 , upon potassium f errocyanid, K 4 Fe(CN) 6 , 
in the presence of a few drops of hydrochloric acid. Treat 
this blue precipitate with an excess of sodium hydroxid, 
and heat to boiling. Notice the reddish brown precipitate 
of ferric hydrate, Fe(OH) 3 . 

Experiment 61. Make some Prussian blue, as in the pre- 
vious experiment, and add to the precipitate, in the test 
tube, a few crystals of oxalic acid, and warm the mixture. 
Notice the intense blue solution obtained (liquid blue). 

Ultramarine is an interesting artificial compound which 
is put upon the market in the shape of small " bluing balls." 
It is similar to the native mineral called " lapis lazuli," and 
is a double silicate of sodium and aluminum containing sul- 
fur. Like indigo, it is insoluble in water and is simply 
held in suspension in that liquid. There is difficulty in 
preventing the formation of blue spots and streaks with 
the solid blue. This blue is extensively used for coloring 
wall paper and for " bluing " white sugar. 

Experiment 62. To show the presence of sulfur in ultra- 
marine, place a part of a bluing ball in water in a test tube, 
and add to it enough hydrochloric acid to make the solution 
acid. Notice the odor of escaping gas when the solution is 



CLEANING : SOAP, BLUING 105 

warmed, and test it for hydrogen sulfid, by holding in 
the gas a paper dipped in lead acetate solution. The paper 
turns black on account of the formation of lead sulfid. 

Aniline colors made from coal tar are the basis of most 
of the liquid blues on the market at the present time. The 
soluble blues from this source are very numerous, and they 
are probably as satisfactory as anything for this purpose. 



CHAPTER IX 

DISINFECTANTS, ANTISEPTICS, AND DEODORANTS 

Since the health of the body depends so largely upon 
sanitary surroundings, it is important to consider what 
assistance modern science can offer to bring about the most 
hygienic conditions in the household. Infection, in general 
terms, is something capable of producing disease that comes 
to the body from without, and this infection usually reaches 
the system by the aid of certain lower forms of life known 
as microorganisms. These microorganisms may be distrib- 
uted by impure water, by house flies, by flying dust, or by 
personal contact between individuals. We may try to check 
the progress of a disease within the body, where it becomes a 
very difficult problem, or, what is better, the attempt may be 
made to prevent the disease from invading the body by keep- 
ing the dangerous microbes out, or destroying them before 
they have an opportunity to enter it. Those substances which 
are capable of checking the growth of the microorganisms, 
but without necessarily killing them, are known as "anti- 
septics"; so all "disinfectants," or destroyers of infection, 
are also antiseptics, but antiseptics are not necessarily 
disinfectants. (The surgeon of to-day deals with wounds in 
such a way as to have the conditions aseptic, — that is, to 
have all germs excluded in the operation, — which is far 
better than attempting to destroy them when once intro- 
duced into the wound.) 1 

1 Sedgwick, " Principles of Sanitary Science and the Public Health," 
pp. 326, 327. 

106 



DISINFECTANTS, ANTISEPTICS, AND DEODORANTS 107 

Those substances that destroy foul odors are often called 
disinfectants. This may be true or it may not. Some 
things destroy foul odors, or, in fact, simply cover them up 
without in the least going to the source of the trouble, and 
they are not disinfectants but simply "odor killer s." The 
American Public Health Association's committee defines 
a disinfectant as, "An agent capable of destroying the 
infective power of infectious material." This does not, 
however, represent the popular view of the subject. Deo- 
dorants, though they may be of great value in their place, 
are not disinfectants or antiseptics. 

Many people are in the habit of relying on the sense of 
smell to prove the presence of injurious as well as dis- 
agreeable substances in the air. The nose is, no doubt, an 
excellent watchman to protect the body, but whether we 
destroy a foul odor or simply overcome it by a more pungent 
one is not for the sense of smell to distinguish, for germs 
that render the air poisonous are not necessarily destroyed 
when no vile odor can be perceived. Because a substance 
is put on the market as a "microbe killer" or a "perfect 
disinfectant," it is not a proof that it is of any value, any 
more than the fact that a patent medicine is advertised as a 
specific for all the ills of the flesh is a proof that it will 
have that effect. 

TESTS FOR DISINFECTION 

These tests may be of three kinds : l — 

First. From the practical experience of those engaged in 
sanitary work. Such diseases as smallpox, diphtheria, and 
scarlet fever have in many instances been contracted after 
months, from the use of clothing that has been about a 
patient, or from the occupancy of rooms where he has been 

1 Dr. Sternberg, American Public Health Association. 



108 SANITARY AND APPLIED CHEMISTRY 

sick. (Books that have been in the sick room have commu- 
nicated disease months after they were removed from the 
room.) If, after an attack of the disease, the rooms have 
been thoroughly disinfected, the disease has been completely 
stamped out in that place. 

Second. Inoculation experiments have been made upon 
animals with infected material, and with the same material 
that had previously been subjected to the action of disin- 
fectants. In the former case the disease was transmitted, 
and in the latter it was not, and thus the efficiency of the 
disinfectant was shown. It is known that in many infec- 
tious diseases the infecting agent is a germ, and in these 
cases the effect of disinfection is to destroy the germ. 
Experiments have been tried upon man with disinfected 
vaccine virus, and with the same virus that has not been 
thus treated, and the vaccination with the first was not 
successful while that with the latter was. In this way the 
efficiency of a disinfectant was shown. 

Third. Experiments are made directly on the disease 
germs, culture experiments as they are called. Here the 
germs are allowed to propagate in such fluids as extract of 
beef, or bouillon, and thus it is possible to study the life- 
history of these germs outside the body, and to learn what 
agents are efficient in destroying them. 

Some bacteria multiply by "division" and others by 
"spores" also, and the latter are more difficult to destroy, 
because the organism is at that time in what may be called 
a resting stage. Often it is possible to prevent the growth 
and development of germs by the use of antiseptics or dis- 
infectants; the germs are not destroyed, but the disease 
is arrested. 

"An ideal disinfectant is one which, while capable of 
destroying the germs of disease, does not injure the bodies 
and material upon which the germs may be found ; it must 



DISINFECTANTS, ANTISEPTICS, AND DEODORANTS 109 

also be penetrating, harmless in handling, inexpensive, and 
reliable. 1 This ideal disinfectant has not yet been discov- 
ered." There are, however, some inexpensive and common 
substances which can be used to destroy the germs of 
disease with good effect. Among the substances used as disin- 
fectant and antiseptic agents, the following may be noted: — 

Sunlight is an excellent disinfectant, if the material can 
be exposed to the direct rays of the sun. It has been shown 
that the bacillus of tuberculosis is killed by direct sunlight, 
and that of typhoid fever also under certain conditions. 
Even diffused light is of value as an adjunct to the other 
methods for the destruction of germs, so there is reason in 
the common practice of "airing" bedrooms, and letting in 
all the sunlight possible for a time every day. 

Dry air is an excellent purifier, especially if accompanied 
by sunlight, chiefly on account of the large number of 
oxidizing bacteria which are present. It will remove 
moisture and often prevent decomposition in this way, 
for moisture is usually the friend of disease and decay. 

Dry earth also allows oxidation and arrests foul odors. 
This fact is utilized in the dry earth closet. 

Charcoal, especially that made from bones, is an excellent 
deodorizer and will remove foul odors quite readily. A 
handful of boneblack sprinkled on a piece of putrefying 
flesh will, after a short time, prevent any foul odors from 
escaping from it. Wood charcoal acts less effectively in the 
same way, but on account of its porosity absorbs gases 
very quickly. 

Experiment 63. Into a bottle containing 200 cc. of 
dilute hydrogen sulfid water, which has the character- 
istic odor, put about 30 grams of boneblack and shake for 
some time. Filter, and, if the conditions have been care- 

1 Price, " Handbook of Sanitation," p. 223. 



110 SANITARY AND APPLIED CHEMISTRY 

fully observed, the filtrate will have no odor of hydrogen 
sulfid gas, as it will have been absorbed by the animal charcoal. 

Quicklime is also used for purposes of disinfection. On 
account of its cheapness, "milk of lime," Ca(OH) 2 , is recom- 
mended, especially in camp sanitation, for destroying foul 
organic matter. Some physicians regard it as efficient as 
chlorid of lime. 

A variety of substances are used to cover up vile odors, 
while they do not pretend to destroy them. The bad smells 
in the house may be overcome by burning sugar, cotton cloth, 
or coffee. (The lack of personal cleanliness may be made 
less noticeable by the free use of perfumes, but this is a 
method belonging to an earlier kind of civilization rather 
than to our own.) 

More effective than any of the methods above noticed are 
the following — in the absence of spores : — 

Heat, at a temperature of 302° F. (150° C), may be used for 
disinfecting, and should be continued for at least two hours. 
A higher temperature, continued for a shorter time, will 
also destroy the bacteria. Sometimes clothing that would be 
injured by moist heat may be treated in this way. The 
goods may be heated in an oven, but should not be folded 
or piled close together. This method has been used for dis- 
infecting by boards of health in large cities, but it is inferior 
to steam at the same temperature, and does not penetrate 
as well. 

Sulfur dioxid, made by the burning of sulfur, is one 
of the oldest agents used for disinfection. A convenient 
way in which to use this is to put several pounds of sulfur 
in an iron kettle, and to place that on bricks in a pan of 
water. Then light the sulfur by means of burning coals, 
or alcohol, and close the room very tightly. Five pounds 
is considered a sufficient quantity for a room containing 
1000 cu. ft. of space. Sometimes a solution of sulfur 



DISINFECTANTS, ANTISEPTICS, AND DEODORANTS 111 

dioxid is simply exposed to the air of the room. Ten 
pounds of the liquid would be necessary for 1000 cu. ft. 
of space. The presence of moisture in the room or on the 
goods greatly assists the operation. The more tightly the 
room is closed, by pasting strips of paper over the cracks 
beside the doors and windows, the better the disinfection 
will be accomplished, and this precaution should not be 
neglected. Clothing and bedding should be opened out as 
much as possible, so as to bring it in contact with the S0 2 
gas, and the room should remain closed at least 24 hours. 
This gas is liable to bleach certain colors, so it should not 
be used with colored fabrics. Liquid sulfur dioxid, con- 
tained in strong steel cylinders, can now be obtained in the 
market. It is extremely convenient to use for disinfection 
as it is only necessary to open the valve and allow the gas 
to fill the room. Sulfur dioxid is, after all, only a surface 
disinfectant, and is said to be effective only against a 
limited number of pathogenic bacteria. 

Carbolic acid, C 6 H 5 OH, is an agent that has often been 
overrated, on account of its penetrating odor, and because a 
small quantity will overcome most other odors. This acid 
of a strength of 1 to 15,000 will prevent decomposition, but 
1 to 1000 will be needed to destroy spores. 1 It is an excellent 
substance to use for washing floors, walls, etc., and for 
disinfecting soiled clothing and discharges, as its antiseptic 
power is great. Although not very soluble in water, a con- 
venient solution can be made by adding it to water till the 
latter becomes saturated, about 1 to 20, or the solubility can 
be increased by the addition of glycerin. 

The cresols, which are found in commercial carbolic acid, 
and are powerful germicides, are constituents of many of 
the disinfecting solutions now on the market, and they are 
believed by some to be superior to carbolic acid. 

1 Price, " Handbook of Sanitation,' ' p. 252. 



112 SANITARY AND APPLIED CHEMISTRY 

Copper sulfate, CuS0 4 5H 2 0, or "blue vitriol," of about 
10 °J strength, is to be recommended, on account of its 
comparative cheapness, especially as a deodorant. It forms 
a blue solution, with water, and is very soluble in that agent. 

Iron sulfate, FeS0 4 7H 2 0, or the " copperas" of com- 
merce, is very efficient for certain purposes. In the propor- 
tion of 2 lb. to a gallon of water, it may be used with 
great convenience and success to purify sink drains and 
cesspools. It may also be sprinkled in places where there 
are foul odors from the decay of organic matter, and they 
will be completely overcome. 

Zinc chloride, ZnCl 2 , is very largely used as a disinfectant 
and a deodorant. As its solution, as well as that of zinc 
sulfate, is colorless, it will not stain the most delicate fab- 
rics, so it can be used on any clothing that is not injured 
by washing. A 5 % or 10 % solution may be used for this 
purpose or for destroying foul odors. 

Potassium permanganate, KMn0 4 , since it is a strong oxi- 
dizing agent, may be used as a germicide in some cases, 
but is rather expensive. The use of this material in the 
purification of cistern waters has already been suggested 
(p. 73). 

Hydrogen peroxid, H 2 2 , is now a commercial article, 
and its aqueous solution is sold at a reasonable price. 
There are some cases where this mild disinfectant may be 
applied with success, as it will destroy the bacillus of ty- 
phoid fever, cholera, and diphtheria quite readily. 

There are, however, more efficient agents in disinfection 
than those that have been mentioned, because under the 
proper conditions they are of sufficient power to destroy the 
spores of disease. 

Fire, it is well known, is effective to wipe out the disease 
germs. Old clothing and bedding would better be burned 
than that an attempt should be made to disinfect it. The 



DISINFECTANTS, ANTISEPTICS, AND DEODORANTS 113 

great fire of London, that followed the plague, no doubt was 
a blessing, in that it actually destroyed the last traces of the 
disease. That was more important in those days than it 
would be now, for they did not know the first principles of 
the science of disinfection. 

Steam heat is one of the most valuable physical agents 
for the destruction of germs, as it kills bacteria at once, and 
spores after a short time. It is especially valuable for the 
disinfection of clothing, textile fabrics, carpets, etc., as it is 
very penetrating. Municipal authorities are making use of 
this method of disinfection on a large scale with great suc- 
cess. If it seems desirable, the material can be subjected 
to quite a high temperature by the use of superheated steam. 
In some communities machines mounted on wheels are 
used. A large apparatus has been introduced which is so 
constructed that the mattresses, bedding, etc., may be intro- 
duced into a chamber, from which the air is exhausted 
by means of a steam jet. Dry steam is then allowed to 
enter, and a temperature of 230° to 240° F. is maintained for 
15 m., after which the steam exhauster again produces a 
practical vacuum, and finally air is drawn through the 
chamber, and the dried materials may be removed. An 
apparatus of this character is used at the New York Quar- 
antine Station. 

Boiling water is one of the most satisfactory materials to 
use for disinfecting purposes. There are very few germs 
that can withstand a boiling temperature for half an hour. 
A temperature of 70° C. will be sufficient to kill the germs 
of cholera, tuberculosis, diphtheria, etc. Hot water is spe- 
cially applicable to textile fabrics. 

Calcium hypochlorite, CaOCl 2 , chlorid of lime, or "bleach- 
ing powder," is a convenient disinfectant to use in some cases. 
The chlorid of lime holds the chlorin in combination very 
feebly, so that the smell of chlorin is always apparent in 



114 SANITARY AND APPLIED CHEMISTRY 

a good sample. The fresh sample should contain from 30 
to 36 °Jo of available chlorin, but if it is exposed to the 
air for a time it loses all its chlorin, so it must be kept 
in a sealed package till used. Calcium hypochlorite, the 
efficient substance in the bleaching powder, is soluble in 
water, but the solution loses its strength if not closely- 
corked. It is decomposed when brought in contact with 
organic matter, and very effectually kills the germs of 
disease. Experiments with chlorid of lime as a disinfect- 
ant were begun as early as 1881, by Koch. They have 
been continued by Sternberg, Jaeger, Mssen, Klein, Duggan, 
and others, and all showed the very efficient character of 
this substance as a true germicide. Chlorid of lime is 
convenient to sprinkle about in the vicinity of bad odors, 
but the odor of the chlorin gas given off is disagreeable and 
in considerable quantities poisonous, and furthermore it lias 
a very destructive action on metals, so it must be used 
with discretion. 

Formaldehyde gas, HCHO, or "formalin," which is a 
40 °fo solution of the gas, is one of the recent disinfectants 
of great merit. It first came into general use in 1892. As 
it is a good germicide, has no injurious effect on fabrics and 
colors, and can be readily applied, it is taking the place of 
sulfur dioxid gas. 

There are several ways of applying the gas : A polym- 
erized formaldehyde, known as "paraform," is sold in 
pastilles, which when heated give off formaldehyde gas; 2 
oz. of paraform for 1000 cu. ft. of space, with an ex- 
posure of 12 hr., is recommended. A large number of lamps 
have been devised for vaporizing the liquid formalin or the 
paraform. Another method of generating the gas is to use 
" baignetti, " which contain a core consisting of 50 grams of 
paraform. As the baignette burns slowly the paraform is 
volatilized to formaldehyde. The objects to be disinfected 



DISINFECTANTS, ANTISEPTICS, AND DEODORANTS 115 

may be sprinkled with formalin, and inclosed in a tight 
box, so that they may be subjected to the vapor for 
several hours. Another method is to wet sheets with the 
solution and hang them in the room, which is tightly 
closed, for some time. Still another method, which may be 
used on a large scale, is to vaporize the formaldehyde gas 
in a retort outside the room, and force it through an opening 
into the tightly closed space. 

Mercuric chlorid, HgCl 2 , or "corrosive sublimate," 
which stands probably at the head of all substances used as 
disinfectants and antiseptics, is a deadly poison. In 
solutions of 1 : 15,000 it stops decomposition, and a 1 : 2000 
solution will kill most bacteria in two hours. If of 
1 : 500 strength, it will act very quickly on bacteria and 
spores. It was said by Koch to exercise a restraining in- 
fluence on the development of the spores of anthrax bacillus, 
even when present in the proportion of 1 : 300,000, but 
recent experiments show that its germicidal power was 
overrated. It is of importance to note, however, that 
mercuric chlorid is not very efficient where there is much 
albuminous material, because it so readily forms with the 
latter an insoluble substance. 

If a wound is produced by a rusty nail or by any blunt 
instrument, so that the flesh is lacerated, it should be 
opened as well as possible, and cleansed with warm 
water and then filled completely with a solution of corrosive 
sublimate (1 to 1000), or a solution of carbolic acid of 5% 
strength should be injected to destroy any dangerous bac- 
teria that may be present. 

Dr. Sternberg recommends the following as a convenient 
solution of corrosive sublimate for general use: — 

Mercury bichlorid 1 oz. 

Copper sulfate 1 lb. 

Water 1 gal. 



116 SANITARY AND APPLIED CHEMISTRY 

The advantage of this solution is that we not only mix 
with the chlorid of mercury a valuable disinfectant, but 
the solution is colored blue, and so it is less liable to be 
used accidentally. It should be marked " Poison." 



PART II 

CHEMISTRY OF FOOD 

CHAPTER X 
USE OF FOODS 

In the consideration of so broad a subject as food, there 
is difficulty at the outset in giving it a satisfactory defini- 
tion. The growth and repair of the body, as well as the 
potential energy by virtue of which the body is able to do 
actual work, need to be taken into account. Food has been 
defined as, "Anything which, when taken into the body, 
is capable either of repairing its waste or of furnishing it 
with material from which to produce heat or nervous and 
muscular work." * It is important to distinguish between 
food and medicine, and to notice that the latter may revive 
some vital action but will not supply the material which 
sustains that action. There are, however, many articles of 
diet, such as tea and coffee, and the food accessories, such 
as spices and condiments, which, although they do not 
strictly come within the above definition, are often useful 
to stimulate the appetite or to make the food more agreeable. 

It is by no means essential that a single food should con- 
tain all the nutrients needed by the body, and in fact it is 
desirable that there should be a variety of food to stimulate 
the appetite and vary the character of the work which the 
organs of digestion are called upon to perform. Food may 
contain substances which must be broken up or decom- 
1 Hutchison, " Food and Dietetics," p. 1. 
117 



118 



SANITARY AND APPLIED CHEMISTRY 



posed by the body before it is of value, or it may contain 
substances which can immediately be taken into the circu- 
lation and utilized. 

Some food is of use because it furnishes nearly all the 
nutritious substances needed by the body, while other foods 
furnish some special material in an economical or agreeable 
form. Some act readily in sustaining the body, or are easily 
digested ; others are economical and offer a maximum amount 
of nourishment at a minimum cost. 

Not only does food sustain the body, but there is a pro- 
vision of nature that animals should derive great pleasure 
and satisfaction from eating, and this pleasure is due to 
both the sense of smell and that of taste; it is difficult to 
consider the function of one without that of the other. 

Since these senses have not been cultivated as highly as 
the others, there is much room for further development; but 
there are some trades, such as that of the tea taster, the 
wine sampler, and the perfumer, where they are cultivated 
and utilized. The student of physiology finds it difficult 
to classify the sense of taste and smell, but it is possible to 
test the relative delicacy of these senses for various sub- 
stances in different individuals. Some experiments l made 
by the author for the delicacy of the sense of taste, with a 
number of persons of both sexes, showed that it was possible 
to detect — 



1 Bitter substance (quinine) . . 

2 Acid substance (sulfuric acid) . 

3 Salt substance (sodium chlorid) 

4 Sweet substance (cane sugar) . 

5 Alkali substance (baking soda) 



By Males 
(1 part in) 



392,000 

2080 

2240 

199 



By Females 
(1 part in) 



456,000 

3280 

1980 

204 

126 



1 Science, Vol. XI, p. 145. 



USE OF FOODS 119 

This showed that the sense of taste for bitter substances 
was far more delicate than for other classes, and that, ex- 
cept in the case of salt, the females could detect smaller 
quantities than the males. A separate set of tests made 
upon the pupils in a large Indian school l showed the same 
order of delicacy. 

The knowledge that man has obtained as to which foods 
are wholesome and which are poisonous is largely the result 
of experience, and this experience was transmitted and grew 
from one generation to the next. Much is due, then, to our 
ancestors, who have had the courage to explore in the realm 
of untasted food. Even now, fatal mistakes in the selection 
of food are sometimes made, and children must in every 
generation be warned against brilliantly colored berries. 

In the early ages the variety of food was not as great as 
now, for the people not only had less skill in preparing and 
less experience in selecting food, but they were obliged to 
depend on the chase, or to use only that food which was ob- 
tained in the immediate vicinity of their dwellings. They 
were not able to draw on all climates as we do, nor could 
they preserve the fruits of one season to consume in another. 
Grain was stored, fruits were dried, and meats were salted 
or dried, but beyond this little was done to preserve food. 

A mixed diet, then, may be considered as evidence of ad- 
vancing civilization. The palate becomes surfeited with too 
much of one kind of food, and so a change is welcome 
to stimulate the appetite. A monotonous diet is often 
a matter of necessity, but as soon as man has the oppor- 
tunity to indulge in a mixed diet he is not slow to take ad- 
vantage of it. With increased civilization the diet becomes 
more mixed in character, and on this account it does not 
interfere with the health to move from one locality or cli- 
mate to another. 

1 Kans. Univ. Quarterly, Vol. II, p. 95. 



120 SANITARY AND APPLIED CHEMISTRY 

There is no doubt that man, as well as the lower animals, 
is benefited by a variety in food. It has been stated that 
"digestion experiments made with one kind of food 
material do not give on the whole as valuable results as 
those in which two or more food materials are used. In 
other words, it appears that with a mixed diet the same 
person will digest a larger proportion of nutriment than 
with a diet composed of a single food material." It is, 
of course, admitted that a mixed diet may present greater 
temptations to overindulgence in food. 

It stands to reason that as some foods are too rich in 
proteids and others contain too large a proportion of carbo- 
hydrates, we should mix these in the proper quantities. 
This we do when we eat "bread and cheese," potatoes and 
beef, or rice, eggs, and milk in puddings. 

As the system adapts itself to a certain kind of food and 
the stomach secretes gastric juice sufficient in kind and 
quantity for that food, it is not advisable after being ac- 
customed to one kind of diet for a long time to change too 
suddenly to one that is entirely different, for indigestion may 
result. 

The food selected should be suited to the habits, age, and 
employment of a person. A sedentary man will not thrive 
on a diet that is too stimulating, nor one engaged in active 
manual labor upon starchy foods alone. The food that is 
readily digested by an adult will be not at all adapted to 
the use of a young child. 

There seems to be an instinctive selection of particular 
classes of foods for special climates — the Eskimo eats 
large quantities of whale blubber or fats; the Congo natives 
live mostly upon the plantain; the Polynesians subsist 
almost wholly on bread fruit. Even in the temperate zone 
we find that less meat is eaten in warm weather. 

Food, in order to be agreeable and wholesome, is usually 
cooked. This is necessary, — 



USE OF FOODS 121 

First, to improve its appearance and to make it more 
agreeable to the eye and thus more appetizing. 

Second, because warm food is often more agreeable than 
cold. 

Third, to improve the flavor and develop the odor, par- 
ticularly in the case of meats. 

Fourth, in order to destroy any parasites or micro- 
organisms that may be contained in the food. 

Fifth, to bring about certain chemical changes in the food, 
that the better adapt it to digestion. 

Sixth, to soften the material so that it may more readily 
be acted upon by the digestive fluids. 

When proteids, such as meat or eggs, are acted upon by 
heat, even if the temperature is not above 170° F., they are 
coagulated and made more solid, but they are not so tough, 
and the bundles of fibers may more easily be torn apart. 
When starchy food, as grains or potatoes, is cooked, the 
granules swell up, the outer cellulose envelope bursts, and 
thus after mastication the digestive ferments have an oppor- 
tunity to come more intimately in contact with the starch. 
According to Sykes, moist heat, even below 185° F., causes 
most starch grains to burst, so that the starch is said to be 
gelatinized. 1 

Food must be of such a character that it will build up the 
tissue of the body and supply it with energy for doing 
work. Incidentally the heat of the body is kept up by cell 
action, or, as one author puts it, "is a by-product n of 
functional activity. It is not necessary nor advisable, 
however, that all the food taken into the body should be 
positively nutritious. It will be a long time before the 
dreams of those who propose that we carry concentrated, 
or perhaps '•synthetic/' 7 foods for several days' rations in 
the vest pocket will be realized. Xot only would such 
1 Hutchison, "Food and Dietetics," p. 378. 



122 SANITARY AND APPLIED CHEMISTRY 

food soon become positively insipid and disagreeable, but 
there is an absolute necessity for a certain amount of inert 
matter to distend the walls of the alimentary canal and 
distribute the nutrient material so that it may the more 
readily be absorbed. 

Too large an amount of indigestible material in the food 
is, on the other hand, not satisfactory, for not only does it 
require of the different organs an undue amount of work in 
handling it, but the indigestible material may act as a 
positive irritant in the stomach and bowels. Too coarsely 
ground cereals sometimes overstimulate and irritate the 
mucous surfaces and thus become a source of impaired 
digestion. 

Not only should the food contain the nourishing material, 
but this should be of such a character that it is just adapted 
to the wants of the body. 

In order to find out what the human body needs for its 
sustenance we may notice either the composition of the 
body, or we may study milk, which is the food provided by 
nature to nourish the young. The body contains the 
following chemical elements : oxygen, carbon, hydrogen, 
nitrogen, phosphorus, sulfur, chlorin, fluorin, silicon, cal- 
cium, potassium, sodium, magnesium, iron, manganese, and 
copper — sixteen in all. 

The fact that these elements are found, however, means 
very little, if we have no information as to how they are 
combined, what proximate substances or compounds they 
form, for these elements might be combined to form innu- 
merable substances. 

According to a recent authority, 1 the body of a man 
weighing 154 pounds is made up of the following com- 
pounds, in approximately the quantities noted: — 

i A. H. Church, "Food," p. 5. 



USE OF FOODS 



123 





Pounds 


Ounces 


Water, found in all the tissues 

Albumen, myosin, etc., found in muscular flesh, 

chyle, lymph, and blood 

Calcium phosphate, found in tissues and liquids, 

but chiefly in the bones and teeth .... 
Fat, distributed through the body .... 
Ossein, or collagen, found in the bones and 

connective tissues 


109 

16 

8 
4 

4 
4 

1 

1 
1 
















8.0 

12.0 
8.0 

7.8 


Creatin, etc., in the skin, nails, and hair . . 
Cartilagan, found in the cartilages .... 
Haemoglobin, a substance containing iron, found 
in the blood 


2.0 
8.0 

8.0 


Calcium carbonate, in the bones 

Neurin with lecithin, cerebrin, and similar com- 
pounds, found in the brain, nerves, etc. . . 

Calcium fluorid, found in the bones and teeth 

Magnesium phosphate, chiefly in bones and teeth 

Sodium chlorid, throughout the body . . . 

Cholesterin, inosite, and glycogen, which are 
found in brain, muscle, and liver .... 

Sodium sulfate, phosphate, carbonate, &c, found 
in all liquids and tissues 

Potassium sulfate, phosphate, and chlorid, 
found in all liquids and tissues 

Silica, found in hair, skin, and bone . . . 


0.8 

13.0 
7.4 
7.0 
7.0 

3.0 

2.2 

1.7 
0.1 



Besides the above there are other complex compounds 
which occur in small quantities, but which are none the 
less of importance. Each of the proximate principles is 
made up of two, three, four, or possibly more, elements, and 
the compounds thus formed are some of them very com- 
plex in their structure. 

No classification of food is very satisfactory, for although 
we may adopt the classification of Liebig and divide the 



124 SANITARY AND APPLIED CHEMISTRY 

foods into the carbonaceous, or those which furnish heat, 
and nitrogenous, or those whose function it is to build up the 
body and furnish muscular energy, we are met at the outset 
by the fact that a large number of foods partially fulfill 
both functions. The cells of the body may draw their sup- 
ply of energy from proteids, albuminoids, carbohydrates, or 
fats ; but material for the manufacture and repair of tissues 
must come from the proteids. Heat is produced as a result 
of cell action. 1 

The proximate substances that go to make up foods 
include (1) water, (2) fat, (3) carbohydrates, (4) protein 
and related nitrogenous bodies, (5) organic acids, and (6) the 
mineral salts. Water, although absolutely essential as a con- 
stituent of the food material, need not be considered in the 
light of a nutrient. The fats which occur both in vegetable 
and animal foods are glycerids of the fatty and other acids. 
They contain only carbon, oxygen, and hydrogen. The 
oxygen is not present in sufficient quantity so that with the 
hydrogen it would form water. Fats are more fully dis- 
cussed under Soap, p. 96, also on p. 49 and in Chapter XVIII. 

CARBOHYDRATE FOODS 

The carbohydrates include, with a few exceptions, only 
those compounds of carbon, hydrogen, and oxygen in which 
the hydrogen and oxygen are in the proportion to form water ; 
that is, two parts of hydrogen to one of oxygen. This group 
includes such common foods as starch (C 6 H 10 O 5 ) n and cane 
sugar (C^H^Ou). These foods may be divided into: — 

1. The cellulose group (C 6 H 10 O 5 ) n , including cellulose, 
starch, inulin, dextrins, gum, etc. 

2. The cane-sugar group (C^H^Ou), including cane sugar, 
milk sugar, maltose, etc. 

1 Hutchison, " Food and Dietetics," p. 3. 



USE OF FOODS 125 

3. The glucose group (C 6 H 12 6 ), including dextrose, levu- 
lose, grape sugar, starch sugar, and galactose. 

In addition to the above, inosite, C 6 H 12 6 ,H 2 0, which oc- 
curs in muscular tissues, and pectose, the jelly-producing 
substance of vegetables, should according to some authors 
be classified as carbohydrates, 

The ordinary analysis of a food stuff includes a determina- 
tion of the amount of water, fat, nitrogenous matter, carbo- 
hydrates, and ash. A study of these analyses is of value 
in the comparison of different foods. 



CHAPTER XI 
CELLULOSE, STARCH, DEXTRIN, ETC. 

Cellulose (C 6 H 10 O 5 ) n is the main product of vegetable life, 
and forms the principal part of wood, cotton, filter paper, 
etc. In fact, cotton fiber, linen rags, and " washed " filter 
paper are nearly pure cellulose. It is insoluble in most 
chemical reagents, but may be dissolved in cuprammonia, 
and from the solution the cellulose may be precipitated as 
a gelatinous mass which is similar to aluminum hydroxid 
in appearance and dries to a hard mass. 

When cotton or paper is treated with a mixture of nitric 
and sulfuric acids, a substance called nitrocellulose is 
formed. One variety of this substance is gun cotton. When 
the nitrocellulose is dissolved in ether it yields collodion. 
Another product known as celluloid is made by dissolving 
certain varieties of nitrocellulose in ether and camphor, and 
afterwards evaporating off the solvent. There are some 
special properties of cellulose, which are illustrated in the 
experiments which follow this section. 

Although some of the lower animals, as the rodents, can 
digest cellulose and make it available for nutrition, the 
stomach of man has this power only to a limited extent. 
According to Atwater some of the cellulose of the food is 
absorbed, but much of it passes through the system un- 
changed and is of value only as it helps distend the alimen- 
tary canal. Whatever digestion takes place in the intestines 
is due to the action of certain microorganisms, by which fatty 
acids are produced, which upon absorption yield nutriment. 

126 



CELLULOSE, STARCH, DEXTRIN, ETC. 127 

Herbivorous animals eat food that contains large amounts 
of cellulose associated with smaller quantities of starch, fat, 
and nitrogenous substances. 

Experiment 64. To 3 volumes of water add 1 volume con- 
centrated sulfuric acid and cool the mixture. Pour this into 
an evaporating dish, and immerse in it strips of unsized 
paper, and allow to soak for about 15 seconds. Wash thor- 
oughly, first with water, then with dilute ammonia solution, 
and again with water. Dry the parchment paper or amyloid 
thus obtained, and notice its peculiar properties. Although 
it has undergone a physical change, it still has the composi- 
tion of paper. Unsized cloth may be treated in the same 
way. 

Experiment 65. Another sample of unsized paper is 
treated with strong sulfuric acid, and allowed to stand for 
5 minutes. It dissolves into a pulpy mass, which is then 
washed thoroughly, and tested with tincture of iodin. If 
a purple color is produced, it is an indication that the 
cellulose has been changed to dextrin. 

Experiment 66. To show the action of alkalies on cellu- 
lose, treat a piece of cotton cloth for 20 minutes with a solu- 
tion of sodium hydroxid of a specific gravity of 1.25. Wash 
and dry, and notice the change in the structure of the fiber. 
This is practically the process used to make " mercerized" 
goods. In this process the linear contraction is about 25%, 
and the increase of strength is 50%. 

Experiment 67. Make cuprammonia (Schweitzer's re- 
agent), Cu (NH 3 ) 4 S0 4 , as follows : Add to a cold solution of 
copper sulfate, Cu SO4, a cold solution of sodium hydroxid, 
filter, wash, and dissolve in concentrated ammonium hy- 
droxid and add a little dilute sulfuric acid. Schweitzer's 
reagent should be freshly prepared, and should be capable 



128 



SANITARY AND APPLIED CHEMISTRY 



of immediately dissolving cotton or fine grades of filter 
paper. It may be used to dissolve cellulose from pectose, 
in working with the microscope. 

Experiment 68. Dissolve cotton or filter paper in 
Schweitzer's reagent, and add to the solution an excess of 
hydrochloric acid. This will precipitate the cellulose, 
which may be washed on a filter so that its properties can 
be examined. 

STARCH (C 6 H 10 O 5 ) x 

The starches are regarded as the most important of the 
foods of this group ; indeed, they form the principal part of 
most vegetable foods. Starch is stored up in seeds, roots, 
fruits, and vegetables, and is adapted for food purposes; 
and so it is utilized by man and the lower animals. As the 
bee stores honey for future use, so the plants store starch 
for the use of the germinating seed, and man takes advantage 
of both kingdoms of nature. The carbohydrates circulate 
through the plant in the form of sugar, but they are stored 
up in the form of starch, and this store can be drawn from 
by the plant in time of need. 

Sources of Starch. — The most important source of starch 
is the cereals. The amount of starch contained in some 
grains is as follows : — 

Per Cent 

Rice 79.4 

Buckwheat flour . . . . 77.6 

Barley 62.0 

Sorghum seed ..... 64.6 
Millet 60.0 

Various roots, tubers, and stems are also sources of starch, 
as follows: 1 — 





Per Cent 


Wheat flour . . . 


. 75.6 


Graham flour . . . 


. 71.8 


Corn meal .... 


. 71.0 


Oatmeal .... 


. 68.1 


Rye flour .... 


. 78.7 



1 For complete composition, see " Foods, " by A. H. Church. 



CELLULOSE, STAKCH, DEXTRIN, ETC. 129 



Per Cent Per Cent 

18.0 Artichokes (gum and inulin) 10. 2 

15.3 Sweet cassava (tapioca) . 30.98 

15.0 Arrowroot (Maranta arundi- 

2.5 nacece) 22.93 

3.5 Onions (pectose, etc.) . . 4.8 

3.0 Radishes (carbohydrates) . 4.6 
2.4 



Potato .... 
Yam .... 

Sweet potato 
Carrots (pectose) 
Parsnips . . . 
Turnips (pectose) 
Beets (pectose) . 

Some less familiar sources of starch are the Bitter cassava 
(tapioca), Salep (orchids), Tous les mois (Carina edulis), the 
sago palm, and celery roots. 

The leguminous plants also furnish starch, thus : — 

Per Cent Per Cent 

Beans 57.4 Peanuts 11.7 

Peas 51.0 Soy beans 12.5 

Lentils 56.1 

There is some starch in all fruits, but those mentioned 
are of special value on account of the amount which they 
contain: — 

Per Cent Per Cent 

Bananas ........ 22.0 Breadfruit 14.0 

Plantain 15 to 20 

Some nuts contain considerable starch, thus : — 

Per Cent Per Cent 

Acorns 43.35 Horse chestnuts . . . .68.25 

Chestnuts 42.1 

Of the above, the most important commercial sources of 
starch are wheat, corn, rice, potatoes, acorns, and chestnuts. 
A special variety of starch is also put on the market 
under the name of tapioca, arrowroot, and sago. The 
other starch-bearing vegetable products, as well as those 
specially noted, are used in some countries as food. 

WHEAT 

The examination of the wheat grains by the microscope 
shows that upon the outside there are bran cells ; next to 



130 SANITARY AND APPLIED CHEMISTRY 

these are cells of a thin cuticle ; within these are the gluten 
cells, and finally, nearer the center of the grain, are the starch 
cells. If a longitudinal section be made of a wheat grain, 
and it is examined by a microscope of low power, it will 
be found to be made up of the " germ," which is near one 
end, the "kernel," and the " bran," or outer envelope. 1 

Wheat is a typical bread-making cereal. Its proteids 
differ from those of other cereals, and are composed chiefly 
of a globulin, an albumin, a proteose, and the two bodies, 
gliadin and glutenin. 2 The two latter form the gluten, and 
give the characteristic properties to wheat flour. The prod- 
ucts of wheat are used as human food in many forms. 
There are nearly a hundred different grades of food materials 
made from wheat by the patent-roller process of milling. 3 

Wheat sown in the fall is called winter wheat, and that 
sown in the spring is spring wheat. The kernels of winter 
wheat are usually larger and softer than the spring variety. 
Spring wheat usually contains more gluten than winter 
wheat. 

In comparing the milling and the food value of wheat, it 
should be remembered that this depends largely on the 
amount of nitrogenous matter present. A high percentage 
of proteids is not always a sure indication of the milling 
value of the wheat. It is the gluten content of the flour on 
which the bread-making qualities chiefly depend. The per- 
centage of dry gluten is considered the safest index to use in 
the comparison of different samples of flour. 

A comparison of the analysis of different samples of 
wheat is of interest: 4 — 

1 For full description, see Jago, "The Science and Art of Bread 
Making," p. 265. 

2 Osborn and Voorhees, Am. Chem. Jour, Vol. XV, p. 392. 

3 Bui. 13, Pt. 9, U. S. Dept. Agric., Div. Chem. 
* Wiley, Bui. 45, U. S. Dept. Agric, Div. Chem. 



CELLULOSE, STAECH, DEXTRIN, ETC. 



131 





MOISTUBE 


Albumi- 
noids 


Ether 
Ext. 


Crude 
Fiber 


Ash 


Carbo- 
hydrates 


Domestic .... 


10.62 


12.23 


1.77 


2.36 


1.82 


71.18 


Foreign .... 
World's Fair, 1893 . 


11.47 
10.85 


12.08 
12.20 


1.78 
1.74 


2.28 
2.35 


1.73 
1.81 


70.66 
71.09 


Mean, given by Jen- 
kins & Winton 
Spring . . . 
Winter . . . 


10.40 
10.50 


12.50 
11.80 


2.20 
2.10 


1.80 
1.80 


1.90 
1.80 


21.20 
72.00 


Mean, by Konig 
Miscellaneous . 


13.37 


12.51 


1.70 


2.56 


1.79 


68.01 


Spring Wheat . 
Russian, Spring 


13.80 
12.56 


14.95 
1 17.65 


1.56 
1.58 




2.19 

1.66 


67.93 
65.74 



There are, however, some special varieties of wheat, 
including a Kussian wheat, that contain more protein. 
Twenty-four analyses of this variety show an average of 
21.56% of nitrogenous substances. 1 The ash of wheat 
contains about 30 % of potash, 3 % of lime, 12 % of magne- 
sia, and 47 % of phosphoric anhydrid, besides the other 
constituents that are usually found in the ash of plants. 
From this it is easy to understand that a large amount of 
mineral matter is taken from the soil by a crop of wheat. 

WHEAT FLOUR 

Wanklyn states that wheat flour has the following com- 
position : — 

Per Cent Per Cent 

Water ....... 16.5 Starch, &c 69.6 

Fat 1.2 Ash 0.7 

Gluten, &c 12.0 

As wheat flour was formerly made, it was crushed between 
millstones, forming a rather coarse product ; this was bolted, 
and gave fine flour, middlings, and bran. 

At the present time, by the roller process, in which the 

1 Blyth, " Foods, Their Composition and Analysis, " p. 146. 



132 



SANITARY AND APPLIED CHEMISTRY 



grain is crushed and sifted repeatedly, a large number of 
grades of flour may be produced. 

The highest grade of flour produced is known as Patent 
flour, while the lower grades are often known as Family, 
Bakers', and Eed Dog flour. The following analyses show 
the percentage of the different products produced from the 
grain, and the grades obtained by different millers : — 



Patent flour . 
Straight flour . 
Bakers' flour . 
Low grade flour . 
Bran .... 
Shorts 
Screenings, waste, &c. 



Arkansas 2 

17.65 
50.35 




100.00 



The commercial value of a flour depends on its color, 
texture, and the quantity of gluten which it contains. The 
character of this gluten also differs under different condi- 
tions of climate and soil. Bakers prefer a flour with a high 
percentage of tenacious gluten, which permits the produc- 
tion of a loaf of bread containing a maximum amount of 
water. This water may be as high as 40 %. 3 In large 
bakeries the best results are obtained by mixing different 
grades of flour. 

ANALYSIS OF DIFFERENT KINDS OF FLOUR 

Some of the constituents of different kinds of flour are 
as follows : 4 — 

1 Snyder, Minn. Agric. Exp. Sta., Bui. 90. 

2 Teller, Ark. Agric. Exp. Sta., Buls. 42, 53. 
8 U. S. Dept. Agric, Div. Chem., Bui. 13, Pt. 9. 
* Bui. 13, Pt. 9, U. S. Dept. Agric, Bu. Chem. 



CELLULOSE, STAKCH, DEXTRIN, ETC. 



133 



Patent wheat flour 
Common market 

wheat flour . . 
Bakers' and family- 
flour . . . 
Indian-corn flour 
Eye flour . . 
Barley flour 
Buckwheat flour 



Moisture 


Nitrogen 
N x 6.25 
Proteids 


Dry 

Gluten 


Ether 

Extract 


12.77 


10.55 


9.99 


1.02 


12.28 


10.18 


9.21 


1.30 


11.69 


12.28 


13.07 


1.30 


12.57 


7.13 





1.33 


11.41 


13.56 





1.97 


10.92 


7.50 





.89 


11.89 


8.75 





1.58 



Nitrogen 

Free 
Extract 



74.76 

75.63 

73.87 
78.36 
73.37 
80.50 
75.41 



For a comparison of the different grades of wheat flour, 
the following table, which gives the results of work done at 
the University of Minnesota, 1 is of interest: — 



Milling Product 


Water 


Protein 
Nx 5.7 


Fat 


Carbo- 
hydrates 


Ash 


Phosphoric 
Acid 


First patent flour 


10.55 


11.08 


1.15 


76.85 


0.37 


0.15 per ct. 


Second pat. flour 


10.49 


11.14 


1.20 


76.75 


.42 


.17 


Straight or 














Standard patent 


10.54 


11.99 


1.61 


75.36 


.50 


.20 


First clear- 














grade flour . . 


10.13 


13.74 


2.20 


73.13 


.80 


.34 


Second clear- 














grade flour . . 


10.08 


15.03 


3.77 


69.37 


1.75 


.56 


"Bed Dog" flour 


9.17 


18.98 


7.00 


61.37 


3.48 


— — 


Shorts .... 


8.73 


14.87 


6.37 


65.47 


4,56 





Bran .... 


9.99 


14.02 


4.39 


65.54 


6.06 


2.20 


Entire-wheat 














flour .... 


10.81 


12.26 


2.24 


73.67 


1.02 


.54 


Graham flour 


8.61 


12.65 


2.44 


74.58 


1.72 


.71 


Wheat ground 














in laboratory . 


8.50 


12.65 


2.36 


74.69 


1.80 


.75 


Gluten flour . . 


8.57 


16.36 


3.15 


70.63 


1.29 






1 Synder, U. S. Dept. Agric, O. Exp. Sta., Bui. 101. 



134 SANITARY AND APPLIED CHEMISTRY 

From the figures in the table it will be seen that there is 
a gradual decrease in the water content from the first patent 
to the " red dog " grade of flour, and there is a noticeable 
increase in the ash from the higher to the lower grades. 
The determination of ash has been taken advantage of to 
determine the grade of a particular sample of flour. 

There is but little difference in chemical composition be- 
tween the first and second grades of patent flour. The 
" standard n patent flour contains about 12 per cent of pro- 
tein, while the wheat from which it was made contains 
12.65%. The second clear and "red dog" samples are 
characterized by a high per cent of protein, fat, and ash. 
Judging by their proximate composition only, these latter 
flours might appear to have a higher nutritive value than 
the higher grades ; but when judged by the character of the 
bread made from them, they must be assigned a much lower 
value (see p. 175). 

The wheat product of the United States for 1903 was 

637,821,835 bu. 

CORN (MAIZE) 

Corn, though coming originally from America, has been 
largely cultivated in some other countries. It grows well 
in temperate and warm climates all over the world. The 
grains keep well, and may be parched, or ground into meal. 
There are a large number of varieties of corn, a special 
variety being adapted to each special climate. 

Some of the preparations of corn are hominy, samp, corn 
meal, cracked corn, cerealin, and a large number of corn 
starches. The examination of the analyses made by the 
Department of Agriculture 1 shows that corn has the fol- 
lowing composition : — 

Per Cent Per Cent 

Moisture 10.04 Crude fiber 2.09 

Albuminoids 10.39 Ash 1.55 

Ether extract (mostly fats) 5.20 Carbohydrates .... 70.69 

1 Bui. 45, Dept. Agric., Div. Chem., p. 25. 



CELLULOSE, STARCH, DEXTRIN, ETC. 135 

Corn is especially rich in fats, although, somewhat deficient 
in nitrogenous matters and mineral salts. It is a very fat- 
tening food, both for man and the lower animals. As it 
was first introduced into Europe as food for lower animals, 
it has been somewhat difficult to overcome the prejudice 
of the people against it, although the United States gov- 
ernment has sent a commission to Europe to demonstrate 
to the people the value of corn as a food. Corn meal is 
quite digestible, though slightly laxative. Cornstarch is 
frequently used as a substitute for other starches in food 
for invalids. In this country, both yellow corn meal, 
made from hard corn of the Northern States, and white 
corn meal, made from the white corn of the West, are in use. 

Referring to the relative nutritive properties of wheat and 
maize, Wiley 1 says : " There is a widespread opinion that the 
products of Indian corn are less digestible and less nutritious 
than those from wheat. This opinion, it appears, has no 
justification, either from the chemical composition of the 
two bodies, or from recorded digestive or nutritive experi- 
ments. In round numbers, corn contains twice as much fat 
or oil as wheat, three times as much as rye, twice as much 
as barley, and two thirds as much as hulled oats. Indian 
corn has nearly the same content of nitrogenous matters as 
the other cereals, with the exception of oats." 

The corn crop of the United States amounted to 2,244,- 

176,925 bu. in 1903. 

OATS 

Oats are grown in northern regions throughout the civilized 

world. The composition of oatmeal is as follows : 2 — 

Per Cent Per Cent 

Water 12.92 Dextrin and Gum ... 2.04 

Nitrogenous matter . . 11.73 Starch 51.17 

Fats 6.04 Fiber ....... 10.83 

Sugar 2.22 Ash 8.05 

1 U. S. Dept. Agric, Div. Chem., Bui. 13, Pt. 9, p. 1290. 

2 Blyth, " Foods, Their Composition and Analysis," p. 170. 



136 SANITABY AND APPLIED CHEMISTRY 

Oatmeal contains considerable fat, protein, and mineral 
salts. The nitrogenous substance is composed of " gliadin " 
and plant casein. The gKadin has a much higher percent- 
age of sulfur than the gliadin of wheat. Von Bibra states 
that oatmeal contains from 1.24 to 1.52% of albumen. It 
has proved an excellent food stuff, though, on account of the 
quality of the gluten, it is not adapted to use for making 
bread. Within the last forty years it has come into extensive 
use in the United States as a breakfast food. It is stated 
that the so-called Scotch groats are prepared by removing 
the outer husks and leaving the grain almost whole, and 
then this is ground between millstones. True Scotch groats 
are heated over perforated iron plates and slightly parched 
before being ground. In most cases where oatmeal can be 
digested, it forms a very valuable food, but it requires long 
cooking and considerable skill in preparation to make it 
wholesome. On this account, although it has been used so 
extensively for many years, recently other foods have to 
some extent been substituted for it. Possibly we have not 
appreciated the fact that it is a very hearty food and es- 
pecially suitable for those who live an outdoor life. The 
oat crop of the United States for 1903 was 784,091,199 bu. 

RYE 

This cereal grows best in northern countries, where it is 
sown in the fall and protected by the covering of snow 
in the winter. It is the favorite food of northern Europe, 
where it is made into "black bread." It was formerly 
quite extensively used as food in the extreme northern part 
of the United States. The grain is also much used for 
malting purposes. It makes a better bread when mixed 
with wheat flour in the proportion of two of wheat to one of 
rye. This grain is more liable than other cereals to be 
affected by the fungus known as ergot. Grain that is modi- 



CELLULOSE, STARCH, DEXTRIN, ETC. 137 

fied in this way is unwholesome and may be poisonous. On 
account of its composition rye dough is very sticky, and of 
a dark color. The composition of American rye is as 
follows : * — 

Moisture Albuminoids Ether Extract Crude Fiber Ash Carbohydrate 
8.6 11.32 1.94 1.46 2.09 74.52 

The rye crop of the United States for 1903 was 129,363,446 
bushels. 

BARLEY 

This grain was originally a native of western Asia, and is 
well adapted to high northern latitudes. Both barley meal 
and " pearl barley, " that is, the grain deprived of the outer 
coating by attrition, are used as food. By far the largest part 
of the barley that is grown is used for making malt (see 
Chapter XXIII). Barley flour does not yield a light bread, 
but may be mixed with wheat flour for this purpose. The 
following is the composition of the grain : l — 



Moisture 


Albuminoids 


Ether Extract 


Crude Fiber 


Ash Carbohydrate 


11.31 


10.61 


2.09 


4.07 


2.44 69.47 



131,861,391 bushels of barley were produced in the United 

States in 1903. 

RICE 

This cereal is a native of India and is grown in the East, 
in southern Europe, and in the southern United States, 
where it was introduced in 1644. For its successful culti- 
vation an abundance of water, so that the fields can be irri- 
gated, and a high temperature are required. Although rice 
is deficient in albuminoids, fat, and mineral matter, yet it is 
estimated that it is the main food of a third of the human 
race. 2 To prepare the grain for the market it is separated 
from the hulls, in a mill of special construction, and for the 

1 Bui. 45, U. S. Dept. Agric, Div. Chem. 
* A. H. Church, "Food," p. 88. 



138 



SANITABY AND APPLIED CHEMISTRY 



European market it is glazed by shaking in a drum lined 
with sheepskin. The grains are also ground into flour or 
may be used for making starch. Rice has the following 
composition, according to Konig : x — 







Moisture 


Albumin- 
oids 


Ether 
Extract 


Crude 
Fiber 


Ash 


Carbo- 
hydrates 


Hulled 
Polished 


12.58 
12.52 


6.73 

7.52 


1.88 

.84 


1.53 

.48 


0.82 
.64 


76.46 
78.00 





This grain is exceedingly digestible when cooked, especially 
by steaming, so that the individual grains are softened and 
swollen. It cannot be made into bread unless mixed with 
wheat or rye flour, as it is deficient in gluten. 

It is evident from the composition of rice that it is not 
fit to use as an exclusive food, but should be eaten with 
butter, eggs, and milk, as in puddings, or with meat, fish, peas, 
or beans, to supply the necessary food ingredients. When 
rice is cooked in a soup or with meat, the mineral salts, which 
at best are not very abundant, are not dissolved in water 
which is thrown away, but are fully utilized in the food. 



POTATOES 

The potato, Solanum tuberosum, is closely allied botani- 
cally to several interesting plants, including the tomato, 
tobacco, henbane, and capsicum. Although a native of Chili 
and Peru, it was probably carried to Spain early in the six- 
teenth century, and introduced into Virginia from Florida 
by the Spanish explorers, and into Great Britain from Vir- 
ginia in 1565 by Sir John Hawkins. 2 The potato was 
recommended by the Royal Society of London in 1663 for 

1 Bui. 45, U. S. Dept. Agric, Div. Chem., p. 34. 

2 Prof. L. H. Bailey, Universal Cyclopedia. 



CELLULOSE, STARCH, DEXTRIN, ETC. 139 

introduction into Ireland as a safeguard against famine. It 
is a question whether its introduction there has not aggra- 
vated the famine tendency, since the peasants learned to 
depend almost entirely on potatoes, and from disease this 
crop sometimes failed. It was not cultivated in New Eng- 
land till the eighteenth century, when it was introduced from 
Ireland; and now this "much traveled " tuber is one of the 
most important articles of food. 

Potatoes grow well and are a staple crop in the New 
England States, New York, Michigan, Canada, and through- 
out the Middle West. Even where the season from frost to 
frost is quite short a good crop may be raised. 247,127,880 
bu. were grown in the United States in 1903. 

The following analysis is given by Church : 1 — 

Per Cent Peb Cent 

Water 75.0 Dextrin and pectose . . 2.0 

Albuminoids 1.2 Fat 3 

Extractives, as solanin and 

organic acids .... 1.5 Cellulose 1.0 

Starch 18.0 Mineral matter .... 1.0 

This shows that 93% of the potato is water and starch, 
and that, as in the case of rice, the amount of fat, albumi- 
noid, and mineral matter is very small. But with even 
this small amount of nitrogenous substance, experiments 
have proved that only 49% of this is proteids, the remain- 
der being ammonium compounds and salts, which are of no 
value as nutrients. The grains of potato starch are very 
large as compared with those of the cereals. Commercial 
starch is readily obtained from this tuber and this is a 
convenient method for utilizing small and immature po- 
tatoes. The starch is also very readily attacked by ferments, 
and so potatoes are often used as an ingredient of home- 
made yeast. 

A cross section of the potato shows that it is made up of 
i A. H. Church, "Food," p. 102. 



140 SANITARY AND APPLIED CHEMISTRY 

a rind, which, constitutes 2\% ; a fibrovascular layer, 8^% ; 
and the flesh, 89%; and an analysis 1 has shown that the 
fibrovascular layer is much richer in mineral matter and 
proteids than the body of the potato, so by the ordinary 
method of peeling, much valuable nutrient material is 
lost. It is estimated that 20% of the actual weight of 
the potato is usually thrown away as refuse. The mineral 
matter is rich in potash salts, and when the potato is peeled 
before boiling, much of this and of the valuable proteid 
matter is dissolved and wasted. If potatoes must be peeled, 
there is less loss of nutrient material if they are plunged 
immediately into boiling water and boiled rapidly. Potatoes 
may also be steamed or baked without appreciable loss. 

Potatoes are evidently not suited for use as the staple 
article of diet, but are extremely useful as food when eaten 
with butter, milk, meat, eggs, and fish, and this is indeed 
the ordinary method of using them. They are very valua- 
ble to prevent scurvy, and usually form a staple article of 
food upon shipboard, where salt meats are necessarily used. 

SWEET POTATOES 

The sweet potato belongs to the convolvulus family, and 
is probably a native of tropical America, though it grows 
well in temperate climates. The yam is a different plant, 
although there is a resemblance between the tubers of this 
plant and the sweet potato. Sweet potatoes have the 
following composition : 2 — 

Per Cent Pee Cent 

Water 75.0 Pectose 9 

Albuminoids, etc. ... 1.5 Fat 4 

Starch 15.0 Cellulose 1.8 

Sugar 1.7 Mineral matter .... 1.5 

Dextrin and gum . . . 2.2 

1 Bui. 43, U. S. Dept. of Agric, Office of Exp. Sta., 1897, p. 30. 

2 Church, « Food, "p. 107. 



CELLULOSE, STARCH, DEXTRIN, ETC. 141 

CASSAVA (TAPIOCA) 

Tapioca is a starch product made from the roots of 
several plants of the manioc family, that grow in parts 
of South America and in other tropical regions. One of 
these, the Manihot utilissima, or bitter cassava, yields a 
milky juice, which in the preparation of the tapioca is 
mixed with the starch, and this contains considerable of the 
poison known as prussic acid, HON. In the preparation 
of the tapioca, this juice is washed away from the grated 
root and the pulp is heated on hot plates, to drive off the 
last of the prussic acid ; this treatment also ruptures most 
of the starch grains. 1 Tapioca is considered one of the most 
useful foods for invalids. A tapioca flour is also made by 
grinding the dried pulp, and this forms the chief food of 
the natives in many tropical countries. " Pearl tapioca " is 
often made from potato starch. 

ARROWROOT 

The commercial arrowroot is made from the rhizome of 
the Maranta arundinacea, 2b plant growing in the West 
Indies. The roots are washed, reduced to a pulp and 
mixed with water, strained, and from the milky water the 
starch settles out. The granules of the starch thus pre- 
pared are among the largest used in commerce. The prod- 
uct when cooked is one of the most valuable foods for the 
diet of invalids. In making the so-called Bermuda arrow- 
root, great care is observed to keep it from contamination. 

SAGO 

This form of starch is made from the pith of the sago 
palm, which grows in Sumatra, Java, Borneo, and the West 
Indies. The starch is washed out of the pith after the tree 

iBul. 44, U. S. Dept. Agric, Div. Chem. 



142 SANITARY AND APPLIED CHEMISTRY 

has been felled, and is converted into " pearl " sago by granu- 
lation. A palm tree frequently yields 500 lb. of sago. 

OTHER STARCHY POODS 

Chestnuts contain 15% of sugar and from 25 to 40% of 
starch. Although used for making bread by the French, 
Spanish, and Italians, it is not a very digestible form of 
starch. 

Some of the other starches of interest are salep, which 
is made in Smyrna, from a species of orchid, and is used 
in Turkey and the East as food ; Tous les Mois, manufac- 
tured in the West Indies from the tubers of Carina edulis ; 
and a starch prepared in Japan from the bulbs of several 
varieties of lily. 

All the more expensive starches are liable to adulteration 
with cheap starches, such as that of wheat, corn, or rice, 
and these adulterations can only be detected by the use of 
the microscope. 

LEGUMES 

Under the general name of pulse may be classified such 
important foods as peas, beans, soy beans, lentils, etc., 
which come from the leguminous plants. It is said that 
peas came originally from the country around the Black 
Sea. Beans were introduced into Europe from India, and 
lentils were grown from the earliest times in southern 
Europe and the country to the east and south of the 
Mediterranean Sea. The soy bean is an important article 
of food in China and Japan, and supplements very well the 
rice diet in these countries. 

These foods are characterized by containing not only 
large quantities of starch, but proteids as well, so they 
may be considered as furnishing, at the same time, both 
kinds of nourishment needed by the body. On this account, 
the legumes are often classified with the nitrogenous foods. 



CELLULOSE, STARCH, DEXTRIN, ETC. 



143 



Plants of this family have a special provision for getting 
enough nitrogen for their growth, in the little nodules on 
the roots, which consist of masses inclosing bacteria, which 
have the power of fixing the free nitrogen of the air so it can 
be utilized by the growing plant. Peas and beans also 
contain some sulfur and phosphorus, in combination with 
the nitrogenous body known as legumin, or vegetable casein. 

Legumin of the unripe peas appears to be more soluble 
and more readily digested than that from the dried seeds. 
On the whole, the leguminous foods are not readily digested 
in the stomach, but are quite thoroughly absorbed in the 
intestines. 1 If, however, the food is not ground to a state 
of very fine subdivision, there is quite a loss of proteids 
in the process of digestion. 

The following analyses are given by Hutchison: 2 — 





Water 


Proteids 


Carbo- 
hydrates 


Fat 


Cellulose 


MITRAL 

Matter 


Green peas . . 
Dried peas . . 
Beans . . . 
Lentils . . . 


78.1 
13.0 
11.7 
11.7 


4.0 
21.0 
23.0 
23.2 


16.0 
55.4 
55.8 

5S.4 


0.5 
1.8 
2.3 
2.0 


0.5 
6.0 
4.0 
2.0 


0.9 
2.6 
3.2 
2.7 



While the leguminous foods are excellent diet, yet they 
should be supplemented by the food containing starch and 
fat, and so we use beans and rice, or, more commonly, baked 
beans and fat pork. In the latter case, the oil or melted 
fat permeates the mass in cooking, and flavors the beans, 
and, at the same time, furnishes a more digestible diet than 
if the same amount of fat was used for frying. 

Experiment 69. To prepare legumin, powder some peas 
and treat the flour with successive quantities of cold water, 
made slightly alkaline. In this solution precipitate the 



1 Hutchison, "Food and Dietetics," p. 223. 



2 Idem, p. 225. 



144 SANITARY AND APPLIED CHEMISTRY 

legumin with acetic acid. To purify, dissolve the pre- 
cipitate in weak potassium hydroxid solution and reprecipi- 
tate with acetic acid. The pure alkaline solution should 
give a violet color, with copper sulfate solution. 1 

Green peas and green beans, as well as " string beans," do 
not furnish a very highly nutritive diet, as they contain 
from 80 to 90% of water, but, on account of the ready 
solubility of the proteids and their agreeable flavor, they 
form a valuable food product. 

On account of the cheapness of this form of proteid 
food, a pea sausage (Erbswurst) has been introduced as a 
part of the rations in the German army. It is a cooked 
food, made of pea meal mixed with fat pork and salt, so 
prepared that it will not readily spoil. 2 In cases where 
it is necessary to economize in the cost of food, this can be 
readily attained by the use of relatively large quantities 
of peas, beans, and lentils, for they contain large amounts 
of nutrients at a comparatively low cost. 

BANANAS 

The banana, although a variety of the plantain family, is 
smaller and more delicate in flavor than the common plan- 
tain. Although the banana grows as far north as Florida, 
yet the climate best adapted to its cultivation is that of 
Cuba, Jamaica, the Congo region in Africa, and especially 
Central America. 

The tree grows to a hight of from 12 to 40 feet. When 
the stalk of the tree is cut down, new stalks shoot up from 
the roots. The tree is propagated on a new plantation, not 
by seeds, but by cutting off roots from old plants, and plant- 
ing in rows, very much like the hills of corn. The banana 
comes to maturity from the root in from ten to twelve 

1 Blyth, " Foods, Their Composition and Analysis," p. 181. 

2 Thompson, " Practical Dietetics," p. 163. 



CELLULOSE, STARCH, DEXTRIN, ETC. 



145 



months. Each bunch that is produced will contain from 
150 to 180 bananas. 

The banana-growing industry has increased enormously in 
the past thirty years, and at the same time the cost of the 
fruit has decreased. Bananas which a few years ago cost 
10 cents apiece can now be bought at from 10 to 15 cents 
a dozen. The fruit is shipped to the United States in fast 
steamers that are capable of carrying 40,000 bunches per 
trip. In 1905, 33,000,000 bunches were shipped into the 
United States, or an estimated consumption of forty bananas 
per year per capita. 

Bananas are peculiar in combining the sweet qualities of 
a fruit with the nourishing qualities of a vegetable. On 
account of the presence of so much nutriment, and because 
bananas grow so luxuriantly, it is stated that a given area 
of ground will support a greater population if planted to 
bananas than if planted with wheat. 

The analysis of bananas compared with some other starchy 
foods is as follows : — 





Ripe 
Bananas 1 


Potatoes 2 


Banana Flour 

from 

Ripe Fruit 3 


Wheat 
Flour 3 


Moisture .... 
Nitrogenous 

substances . . 

Fat 

N.-free extract . 
Carbohydrates 
Cellulose . . . 
Ash 


73.10 

1.87 

.63 

23.05 

.29 
1.06 


78.3 

2.2 

.1 

18.4 

1.0 


13.0 

4.0 
.5 

80.0 

2.5 


13.8 

7.9 
1.4 

76.4 

.5 



From this analysis it is evident that bananas are rich in 
sugar or starch and contain a fair quantity of proteids. 

i Konig, " Chem. d. M. Nah. u. Genuss.," p. 1120. 
2 Rep. Ct. Agric. Ex. Sta. 3 Hutchison, p. 249. 

L 



146 SANITARY AND APPLIED CHEMISTRY 

Some persons find bananas difficult of digestion, but this 
is no doubt due to the fact that they are often picked so 
green that they are irregularly ripened. The imperfectly 
ripened fruit is composed chiefly of starch, and this should 
be cooked before it is eaten, especially by invalids. As the 
fruit ripens naturally, however, this starch changes to a mu- 
cilaginous substance, and then to dextrin and glucose. 

A banana flour is made by carefully drying selected and 
fully ripened bananas. It is said to be easily digested and 
extremely nutritious. This is about the only fruit flour that 
can be readily made, and so it has been used with success as 
a part of the diet of patients suffering from gastric irrita- 
bility and similar diseases. A plantain meal is made by 
drying the inside of the unripe fruit. 

GENERAL METHOD FOR MAKING STARCH 

In the United States starch is made especially from corn 
(maize), wheat, and potatoes ; in Europe, potatoes, corn, and 
rice are used ; and in the West Indies starch is made espe- 
cially from arrowroot or the sago palm. 

Several processes are used for the manufacture of starch. 
In making cornstarch by the Durgen system a continuous 
stream of water at 140° F. is allowed to flow over the corn 
for three days in order to soften it. It is then ground in 
water, and the milky liquid is run into nearly horizontal 
revolving sieves, or square shaking sieves. The starch 
passes through the bolting cloth, and the refuse, which con- 
sists of the cellular tissue, is retained. The refuse is after- 
wards pressed and used for cattle food. The water, holding 
the starch in suspension, is allowed to stand in wooden vats 
until the starch settles out, when it is finally drawn off. 
In order to purify the starch and remove the gluten, the 
crude starch is agitated with a solution of caustic soda, 
allowed to settle, and the clear liquid drawn off. Next 



CELLULOSE, STARCH, DEXTRIN, ETC. 147 

the starch is washed and run into a deep vat, and the high- 
est of a series of plugs is removed from the side to allow 
the starchy liquid to run out. A little later a lower plug is 
removed, and so on until the vat is nearly empty ; then a 
fresh lot of starch water is run in. The products from 
the different lots of starchy water drawn off are of different 
grades and used for different purposes. After again sifting 
through bolting cloth, the starch solution is run into wooden 
settling boxes, and when sufficiently compact is cut into 
blocks and dried on an absorbent surface of plaster of 
Paris in a current of warm air. It is important that the 
temperature of the moist starch be not raised above 60° C. 

In another process the milky liquid is run upon an inclined 
settling floor, and made to run slowly back and forth 
toward the lower end of the room. The starch is deposited 
and the clear water run off at the lower end. Sometimes 
alkali is not used, but the germ of the corn is mechanically 
removed before the starchy part of the corn is ground. 

In making wheat starch the softened grain is sometimes 
ground and then allowed to ferment in large tanks at 20° C. 
for 14 days, with frequent stirring. By the fermentation 
which takes place the gluten is attacked and the starch 
grains are set free. The impure liquid is drawn off and the 
starchy mixture is poured through revolving sieves or made 
to pass through the meshes of hempen sacks. The subse- 
quent operations are like those above described. 

By another process wheat flour is mixed with water, and 
the dough is washed repeatedly in bags under a jet of water. 
Starch is obtained from the water by running it into settling 
tanks, and the gluten which remains in the bags may be 
utilized for making macaroni. 

Experiment 70. Mix a handful of flour with water, and 
place the dough in a cloth bag, and hold under a stream of 



148 SANITARY AND APPLIED CHEMISTRY 

running water, kneading constantly with the hands. The 
starch will be carried away with the water and the gluten 
will remain in the bag. Dry the contents of the bag, and 
examine its structure. 

The insoluble proteids of wheat obtained by kneading a 
dough of wheat flour in a stream of water consist of about 
75 % of true gluten (gliadin and glutenin), together with 
small percentages of non-gluten proteids, mineral matter, 
fat, starch, fiber, and other non-nitrogenous matter. 1 

Experiment 70 a. As the value of a flour for baking 
bread depends on the amount of gluten present, the follow- 
ing method has been used to compare the gluten-content of 
flours. 2 Place 10 g. of flour, wet with an equal weight 
of water, in a porcelain dish, and work into a ball with a 
spatula, taking care that none adheres to the dish. Allow 
the ball to stand for an hour, then knead it with the hand 
in a stream of cold water until the starch and soluble mat- 
ter are removed. Allow the ball of gluten to remain in 
cold water for an hour, then roll into a compact ball with 
the hands, place in a watch glass, and weigh ; this is moist 
gluten. Dry for 24 hours on a water bath and again weigh, 
and then record the weight as that of dry gluten. 

SUBSTANCES RELATED TO STARCH 

Dextrin (C 6 H 10 O 5 ) is .a substance that suggests gum in its 
properties, and indeed it is put upon the market under the 
name of British gum. Several varieties of dextrin exist, 
and it is evident from a study of their composition that 
they may result from the breaking down of the starch 
molecule, by means of dilute acids or ferments. 

Commercial dextrin is made either by heating starch or 
flour to a temperature of 210-280° C, or by moistening the 

i Norton, J. Am. Ch. Soc, 1906. 

2 Wiley, " Agric. Analysis," Vol. Ill, p. 435. 



CELLULOSE, STARCH, DEXTRIN, ETC. 149 

starch with a mixture of dilute nitric and hydrochloric acid, 
slowly drying the paste, and heating it to a temperature 
between 110° and 159° C. 

Dextrin obtained by either of these processes is a white or 
yellowish powder. As it is mostly of the variety known as 
erythrodextrin, its aqueous solution gives a brown color 
with iodine. It is slightly soluble in dilute alcohol, but 
insoluble in 60% alcohol. The brown crust on the outside 
of a loaf of bread is composed mostly of dextrin. Dextrin 
is used on the back of postage stamps to make them adhe- 
sive. 

The Gums are colloidal bodies occurring in the juices of 
plants. They either dissolve or swell up when brought in 
contact with cold water. Some of the more important gums 
are: Gum Arabic, Gum Tragacanth, and the Pectin of un- 
ripe fruit. Their food value has only been imperfectly 
studied. 

Inulin (C 6 H 10 O 5 ) is a starchlike substance found in chic- 
ory, potatoes, artichokes, elecampane, dahlias, and dande- 
lion roots. It is a white powder, readily soluble in boiling 
water, and converted into levulose by boiling with water or 
acids. 

PHYSICAL PROPERTIES OF STARCH 

Starch is really made up of little grains, those of different 
plants being of different size and shape, and showing con- 
centric markings. This indicates that the grains are built 
up of different layers ; that is, a layer of true starch and 
then a layer of a kind of cellulose. These grains are not 
soluble in cold water, alcohol, or ether, so they are not 
washed away when the plant is broken. If boiling water is 
poured upon the starch, or if starch is heated to from 70 to 
80° C, the grains burst and the whole forms a gelatinous 
mass, having, when dry, the stiffening properties with which 



150 SANITARY AND APPLIED CHEMISTRY 

we are familiar. In order to thoroughly cook starch so that 
it shall be digestible, it should be noted that, at some time 
in the process, is should be heated as high as 100° C. Boiled 
with water for a long time, the starch goes into solution, 
1 part dissolving in 50 parts of water. In the process of 
cooking starchy foods, the grains are ruptured, and in this 
condition they are much more easily attacked by the diges- 
tive fluids. 

Experiment 71. Place some starch in a test tube with a 
little water and shake moderately, then filter and test the 
filtrate for starch by adding tincture of iodine (see Experi- 
ment 76). If there is no blue color, how is this accounted for ? 

As all starches are of practically the same composition, 
the only way of detecting the source of any specimen of 
starch is by the use of the microscope. Although there 
are so many varieties, yet the grains of each differ from the 
others in size or shape, or in their appearance with polarized 
light. The expert can thus detect adulterations and the 
substitution of a cheap starch for an expensive one. For 
illustrations of the different starches, see Leach (plates). 

CHEMICAL PROPERTIES OF STARCH 

When starch is heated to 100° C. it changes gradually to 
soluble starch. At a temperature of 160° to 200° C. it is 
changed to dextrin (C 6 H 10 O 5 ) n ; from 220° to 280° C. it 
is changed to pyrodextrin, which is soluble in alcohol. Of 
course if heated still higher, it is decomposed and gives off 
combustible gases. 

Experiment 72. Prepare starch from potatoes by peeling, 
scraping to a pulp, putting in a cloth bag with water, and 
squeezing out the milky juice. Allow this to settle (not 
over 24 hr. ), pour off the clear liquid, and dry the resi- 
due at a temperature not above 70° C. on a water bath. 



CELLULOSE, STARCH, DEXTRIN, ETC. 151 

Experiment 73. Make starch from corn meal and from 
acorn meal, by grinding with water in a mortar and treating 
as in Experiment 72. 

Experiment 74. Make an emulsion of green bananas, 
and prepare starch from this, as above. 

Experiment 75. Make starch paste by mixing a few 
grams of one of the specimens of starch prepared above 
with cold water and pouring this into 100 times as much 
boiling water and heating for a short time. 

Experiment 76. Test a small portion of this starch paste, 
after cooling, with a few drops of tincture of iodin. ( This 
is made by dissolving iodin in alcohol.) A blue color in- 
dicates the presence of starch. 

Experiment 77. To make dextrin (C 6 H 10 O 5 ) n , heat about 
20 g. of starch very cautiously in a porcelain evaporating 
dish, with constant stirring. The temperature should be 
between 210° and 280° C. 

Experiment 78. Another method of making dextrin is to 
moisten about 10 g. of starch with dilute nitric acid, 
dry the paste on a water bath, and finally heat slightly 
above 100° C. 

Experiment 79. Dissolve some of the dextrin made above 
in cold water ( characteristic test) ; add to this solution 
an excess of alcohol, to precipitate the dextrin, filter, and 
wash with alcohol. 

Experiment 80. Prepare Fehling's solution as follows : — 

(a) Dissolve 34.639 g. of copper sulfate in 500 cc. 
of water. 

( b ) 178 g. of Eochelle salts and 30 g. of sodium hy- 
droxid are dissolved in water and diluted to 500 cc. 



152 SANITARY AND APPLIED CHEMISTRY 

Experiment 81. Test a portion of the dextrin made in 
previous experiments, dissolved in water, 

(a) for starch with tincture of iodin, 
(p) for sugar (dextrose) with the Fehling's solution, 
mentioned above. 

By the action of dilute acids the change known as 
hydrolysis takes place in the starch, and dextrin and 
maltose are at first produced ; these are changed by pro- 
longed boiling to dextrose (CeH^Oe). 

Experiment 82. Fehling's Test for Dextrose. To a dilute 
solution of commercial glucose, contained in a medium- 
sized test tube, add 5 cc. of a and 5 cc. of b, and boil for 
a few minutes. The formation of a yellowish red, or, in 
case of an excess of dextrose, of a red flocculent precipitate 
of cuprous oxid, Cu 2 0, indicates dextrose. 

Experiment 83. Conversion of Starch to Dextrose. Use 
about 3 g. of the starch made above; mix with 200 cc. 
of water and 20 cc. dilute HC1. Heat on a water bath in a 
flask for 2 hours, or boil for 15 minutes. Cool, neutralize 
with sodium hydroxid, and test a portion of the solution 
by Fehling's solution for dextrose. 

Many ferments like the ptyalin of saliva, or the pancre- 
atic ferment, change starch to sugar (dextrose). 

Experiment 84. Filter some saliva, and digest this with 
starch paste in a test tube, kept in a water bath at a 
temperature not above 98° F. (36.6° C.) for 15 min. Test 
half of the solution for starch and the other half for 
maltose by Fehling's solution. 

If starch is digested with the diastase of malt, what 
is known as "hydrolysis" takes place and the starch is 
changed to maltose, C^H^Ou + H 2 0, which resembles 



CELLULOSE, STARCH, DEXTRIN, ETC. 153 

dextrose. The action of malt upon starch is expressed by 
the equation : — 

(C 6 H 10 O 5 ) 3 + H 2 = C 6 H 10 O 5 + C^H^Ou. 

Starch Dextrin Maltose 

Experiment 85. Prepare malt extract by digesting 
coarsely pulverized malt for several hours with enough 
alcohol to cover it. Filter and set the solution aside. 
When the alcohol has evaporated, dissolve the residue, 
which contains the ferment known as diastase, in water. 
Make a thin starch paste, cool to about 62° C, add a little 
of the diastase, and digest for 15 m. at this temperature. 
Test a portion of the solution for starch. If it is still 
present, continue the digestion, but if it is all converted, 
test for maltose by Fehling's solution. 

Strong nitric acid in the cold acts upon starch, producing 
several nitroamyloses, collectively known as xyloidin. 
These resemble nitrocellulose (see p. 126). 



CHAPTER XII 
BREAD 

Whether we consider the white bread of the American 
housewife, the black bread of the German peasant, the 
oatmeal " scones " of the Scotch laborer, or the corn " pone " 
of the Southern plantation, each is a valuable nutrient and 
a staple food in its locality. 

Bread consists practically of flour, with the addition of a 
little salt and water, mixed into a paste and baked before a 
fire. The simplest flour is . that made by the natives of 
many countries, by grinding, or "braying," the grain 
between two stones. This was one of the earliest mortars 
used. It is quite probable that the name " bread " comes 
from the word " brayed, " referring to this method of 
breaking the grain. 

There are two general methods of making dough light: — 

1. By nonfermentation methods. 

2. By fermentation methods. 

BREAD NOT RAISED BY FERMENTATION 

There are a large number of methods used for making 
dough light without the use of yeast. Unleavened bread 
is the simplest form of this food and is made without any 
aeration, by mixing the flour and water and baking. Ex- 
amples of this kind of bread are the passover cake of the 
Israelites, the sea biscuit and hard tack used on shipboard 
and in the army, the Scotch oat cake, and the corn-meal 
"pone" so extensively used in the South. Graham and 
whole-wheat flour are used in the same way, thus making 
a bread that is claimed to be more wholesome, and which 

154 



BREAD 155 

may be kept for a much longer time than the ordinary 
raised bread. Unleavened bread is not, however, considered 
as appetizing as raised bread, but has the advantage that 
on account of its hardness and dryness it must be thoroughly 
masticated and mixed with the saliva, and thus becomes 
more readily digested. 

Many processes have been devised for making the dough 
light without the use of yeast. The object of these is to 
shorten the time and labor of making the bread. The fol- 
lowing methods may be noticed, and will serve to show that 
much thought has been devoted to the subject. 

1. By mixing Graham flour or wheat flour with water, 
or milk, and beating it vigorously for some time, and baking 
quickly in cast-iron pans, a fairly light bread results. The 
raising substance in this case is the air that is entrapped 
in the dough. Gems and muffins are made in this way in 
some dietary establishments. 

2. A modification of the above plan is to mix the mate- 
rials with snow, and then bake quickly in a hot oven. In 
this case the cook depends on the air that is entrapped in 
the snow crystals to raise the dough. 

3. Eggs, beaten to a froth, will entangle sufficient air to 
make dough very light and spongy. This fact is taken 
advantage of in the manufacture of sponge cake. 

4. Brandy, wine, or any liquor, diluted, may be used in- 
stead of the water, in the mixing of dough, and when this is 
baked the expansion and volatilization of the alcohol will 
raise the dough. It is probable that very little of the 
alcohol will remain in the finished product, but there are 
some objections to this method, both on account of its ex- 
pense, and because of the flavor of the liquor that remains. 

5. Ammonium carbonate (]STH 4 ) 2 C0 3 is an extremely 
volatile substance, and if a solution, or the fine powder, 
be mixed with the flour, it will, as it escapes in the process of 



156 SANITARY AND APPLIED CHEMISTRY 

baking, raise the dough. This has been used with yeast, 
by the baker, to obtain very light bread. The ammonia salt 
is also used to overcome any excess of acids due to the over- 
fermentation. 

6. Sodium bicarbonate (NaHC0 3 ), when heated, gives off 
a part of its carbon dioxid gas and some water ; and as this 
escapes it will render the dough light. There is, however, 
a great disadvantage in the use of this substance, as there 
remains in the bread sodium carbonate, an alkaline sub- 
stance that renders the bread unwholesome. 

7. A modification of this process, however, will give an 
excellent product. If the baking soda is used with mo- 
lasses, which usually contains some free acid, then the alkali 
is neutralized, and carbon dioxid is set free, and the material 
is very light. This is taken advantage of in making ginger- 
bread. If the molasses is not sufficiently acid, a little vine- 
gar may be added to it. 

8. Aerated bread, as made by Dr. Dauglish, was intro- 
duced a few years ago, and for a time seemed to be so 
popular in this country that there was a prospect of its 
replacing the other varieties that were on the market, but 
it has not found favor here in recent years. It is used ex- 
tensively abroad, especially in London. It possesses a 
characteristic taste that is entirely different from that of 
fermented bread. In the manufacture of this bread the 
flour is mixed in a strong iron vessel, provided with a me- 
chanical stirer, with salt, and water that is impregnated with 
carbon dioxid gas. The dough is forced out of the apparatus 
by the pressure of the gas, and is molded into loaves, that 
are immediately placed in the oven. The vesiculation is 
produced by the carbon dioxid gas, which, in its efforts to 
escape, raises the dough. There is no chemical change in 
the flour, as in fermentation methods of making bread, and 
so none of the flour is lost in the process. 



BREAD 157 

9. A process that is somewhat allied to this, but one 
that has not been received with very much favor, is to mix 
the flour with baking soda, and then to add to the water 
that is to be used in the mixing of the bread sufficient 
hydrochloric acid to combine chemically with the soda ; and 
in this way there would be left in the bread nothing but 
common salt, in accordance with the equation — 

NaHC0 8 +HCl = ]STaCl+H 2 0+C0 2 . 

10. By the use of sodium bicarbonate and freshly curdled 
sour milk, excellent results may be attained. In this case, 
there is left in the bread sodium lactate, an entirely harm- 
less salt, and carbon dioxid gas is set free. Some skill is of 
course required to get sufficient soda in the material to ex- 
actly combine with the acid of the milk. One teacup of sour 
milk will usually neutralize a teaspoonful of baking soda. If 
the milk is not acid enough for the purpose, it may be acidi- 
fied still further by the addition of some vinegar. Biscuit 
and cakes are not only raised by this process, but they are 
rendered richer by the fat and the casein of the milk. If 
too much soda is added, the product is, of course, yellow, 
alkaline, and unwholesome. The equation is — 

NaHC0 3 +C 2 H 5 OCOOH=C 2 H 5 OCOONa+H 2 0+C0 2 . 

Lactic acid Sodium lactate 

11. Sodium bicarbonate and cream of tartar are often 
used to render dough light. The first of these may be 
mixed with the flour, and the latter with the water that is 
used in mixing the dough, or both may be sifted and mixed 
with the flour. This is an excellent method, as the only 
salt remaining in the bread is " Eochelle salt," a compara- 
tively harmless substance, though in large quantities it acts 
as a laxative. The proportions of each substance to be used, 
as estimated from the molecular weight, are one part of 
sodium bicarbonate to two parts of cream of tartar. As the 



158 SANITARY AND APPLIED CHEMISTRY 

powders do not differ very much in bulk, they may be 
measured with a teaspoon. The equation representing the 
reaction that takes place is as follows : — 

KHC 4 H 4 6 + NaHC0 3 = KNa C 4 H 4 6 + C0 2 + H 2 0. 

12. By the use of baking powders. These powders are 
of three kinds : — 

1. Cream-of-tartar powders. 

2. Phosphate powders. 

3. Alum powders. 

The use of baking powders is more common in the United 
States than abroad. It is said that the amount consumed in 
one year will amount to more than 50,000,000 pounds. The 
only thing added to the soda and cream of tartar or other 
substance furnishing the "acid" in the manufacture of a 
baking powder is some starch or flour, which is known as a 
" filler." This is said to be necessary to prevent the ingre- 
dients from combining too soon. In all the powders baking 
soda is used to afford the requisite amount of carbon dioxid 
gas, the only difference between them being in the acid 
salt or chemical used to set it free. 

It is but fair to state that the amount of available carbon 
dioxid obtained from a powder may depend not only on the 
quality of the constituents, the skill with which they are 
mixed, and their correct proportion, but also largely upon 
the age of the powder. The bicarbonate of soda and the 
acid potassium tartrate in the cream-of-tartar powders, or 
the bicarbonate of soda and the sodium or ammonium sul- 
fate, or the alum, in the so-called alum powder, will gradu- 
ally combine, especially if they are not absolutely dry, as 
long as powder is kept in stock, and so the strength of the 
powder will be diminished. Of the thirty-one samples of 



BREAD 159 

baking-powder recently examined by the author, six were 
cream-of-tartar powders, two phosphate powders, fifteen 
alum-phosphate and eight alum powders. The amount of 
available carbon dioxid varied from 1.41% to 15.29%. 

12. Tartrate powders consist of acid potassium tartrate 
or tartaric acid, sodium bicarbonate, and flour or starch. 
The tartrate is made from " argols," that are collected in 
the bottom of wine casks in the process of fermentation. 
The value of a baking powder depends on the per cent of 
carbon dioxid gas that is set free when the powder is put 
into water. The reaction is the same as shown in No. 11. 

Experiment 86. To show the evolution of carbon dioxid 
from a baking powder, place some of it in a 250 cc. flask, 
provided with a cork through which passes a delivery tube 
having its outer end below the surface of 100 cc. of lime 
water placed in a beaker. When water is added to the 
baking powder, the gas is rapidly evolved and produces a 
precipitate in the lime water : — 

Ca(OH) 2 + C0 2 = CaC0 3 + H 2 0. 

Experiment 87. Test a baking powder for flour or starch 
as mentioned in Experiments 75 and 76. 

A powder of the cream-of-tartar class by a complete 
analysis would show the following constituents : 1 — 

Per Cent 

Total carbon dioxid (C0 2 ) 12.25 

Sodium oxid (Na 2 0) 11.03 

Potassium oxid (K 2 0) 11.71 

Calcium oxid (CaO) . . . ... . . .19 

Tartaric acid (C 4 H 4 6 ) 35.14 

Sulfuric acid (S0 3 ) .12 

Starch 18.43 

Water of combination and association, by difference . . 11.13 

100.00 
1 Bui. 13, Pt. 5, U. S. Dept. Agric, Div. Chem. 



160 SANITARY AND APPLIED CHEMISTRY 

The available carbon dioxid was found to be 11.13%. 
This powder would then be made from about 25 parts of 
sodium bicarbonate, 50 parts of cream of tartar, and 25 parts 
of starch. The small quantities of other substances are 
accidental impurities in the chemicals used. Sometimes a 
little ammonium carbonate is used with the above powder. 
As this is really a mixture of ammonium carbamate and 
carbonate, the reactions at first would be : — 

KE 4 C0 2 NH 2 = 2 NH 3 + C0 2 . 

Ammonium Carbamate Ammonium Carbonate 

and (NH 4 ) 2 C0 3 = 2 NH 3 + H 2 + C0 2 . 

Therefore the ammonia salt is entirely volatilized by the 
heat of the oven. 

Experiment 87 a. To test a baking powder for ammonium 
carbonate, place about 15 g. in a beaker, and over this put 
a watch glass carrying on its under side a moistened slip 
of red litmus paper. If the beaker is warmed carefully 
on an iron plate or stove, the ammonia, if present, will, 
after some time, color the paper blue. 

Experiment 87 b. To test for tartaric acid or a tartrate 
in a baking powder, place about 10 g. in a beaker, add water, 
and after a short time filter off the starch and insoluble ma- 
terial. To the filtrate add a little copper sulfate solution 
and some sodium carbonate, and boil the solution for a few 
minutes. Filter off any copper hydroxid that may be 
present and dilute the filtrate about four times. If the 
solution is a distinct blue, especially after adding more 
sodium carbonate and boiling again and filtering, this indi- 
cates the presence of tartrates. 1 

13. Phosphate powders are made from the acid phos- 
phate of lime, — often called superphosphate, — sodium 

1 Bailey and Cady's " Qualitative Analysis," p. 248. 



BKEAD 161 

bicarbonate, and starch. The phosphate is made by the ac- 
tion of sulfuric acid on bones, consequently it sometimes 
contains a little calcium sulfate, but a small quantity is not 
considered an adulteration. The reaction that takes place 
is as follows : — 

CaH 4 (P0 4 ) 2 + 2 NaHC0 3 = CaHP0 4 + Na 2 HP0 4 + 2 C0 2 

+ 2H 2 0. 

The substances that are left in the bread are considered 
about as harmless as the Eochelle salts, and are by some 
thought to be of actual value to the system. On analy- 
sis these powders are shown to have the following com- 
position : * — 

Pee Cent 

Total carbon dioxid (C0 2 ) 13.47 

Sodium oxid (Na 2 0) 12.66 

Potassium oxid (K 2 0) .31 

Calcium oxid (CaO) 10.27 

Phosphoric acid (P 2 5 ) 21.83 

Starch 26.41 

Water of combination and association, by difference . . 15.05 

100.00 

Available carbon dioxid 12.86. This powder would be 
made up of about the following ingredients : — 

Pee Cent 

Sodium bicarbonate 26 

Acid calcium phosphate 37 

Starch 27 

Water of association, &c 10 

Experiment 88. To test for phosphoric acid, ignite about 
5 g. of the powder in a porcelain dish, heat the residue 
with nitric acid, dilute, and filter. To the filtrate add am- 
monium molybdate, and warm (do not boil), when the for- 
mation of an abundant yellow precipitate of ammonium 

1 BnL 13, Pt. 5, U. S. Dept. Agric, Div. Chem. 

M 



162 SANITARY AND APPLIED CHEMISTRY 

phosphomolybdate shows the presence of phosphoric acid. 
It should be remembered that the ash of flour will show a 
small quantity of this acid. 

14. Alum powders are often mixed with phosphate pow- 
ders, and indeed Professor Mallet states that he finds that 
this is usually the case. The alum used is ammonia alum, 
if this is the cheapest, though sometimes " cream-of-tar- 
tar substitute " (calcined double sulfate of aluminum and 
sodium) is used. If alum is used, the equation would be — 

2 NH 4 A1(S0 4 ) 2 + 6 KaHC0 3 = 2 Al(OH) 3 + 3 Na 2 S0 4 

+ (NH 4 ) 2 S0 4 + 6 C0 2 . 

The analysis of a powder of this class shows the follow- 
ing constituents : * — 

Per Cent 

Total carbon dioxid (CO^ 7.90 

Sodium oxid (Na 2 0) 6.99 

Calcium oxid (CaO) .12 

Aluminum oxid (AI2O3) 3.65 

Ammonia (NH 3 ) 1.02 

Sulfuric acid (S0 3 ) 10.11 

Starch 45.41 

Water of combination and association, by difference . . 24.80 

100.00 
Available carbon dioxid 6.41 

This powder would, therefore, be made from about the 
following constituents : — 

Per Cent 

Sodium bicarbonate 21 

Ammonia alum (anhydrous) ...... 15 

Starch 45 

Water of crystallization and association .... 19 

In this particular powder the amount of available carbon 
dioxid is low, but this is probably because the powder had 

1 Loc. cit. 



BREAD 163 

been in stock for some time. Alum powders will give as 
much available carbon dioxid as any others. 

Many experiments have been made to decide exactly what 
is left in the bread when alum and phosphate powder is 
used. From these investigations it is shown that the 
powder which contains enough phosphate to combine with 
the alum is a better powder than the one consisting of 
alum alone. This is so because the phosphate is less 
liable to be soluble than the hydrate of aluminum. It was 
also proven that the interior of a loaf of bread seldom 
reaches the temperature of 100° C, and, on this account, the 
aluminum hydrate will not be dried sufficiently to render it 
insoluble. Professor Mallet says : " A part of the aluminum 
unites with the acid of the gastric juice and is taken up 
into solution, while at the same time the remainder of the 
aluminum hydroxid, or phosphate, throws down, in 
insoluble form, the organic substance constituting the 
peptic ferment. " 1 From experiments made upon himself, 
he concludes that aluminum hydroxid taken into the system 
tends to produce indigestion. 

Experiment 89. To test for sulfuric acid, ignite about 
10 g. of baking powder in a porcelain or platinum dish, cool, 
and boil in a beaker with strong hydrochloric acid until 
nearly all dissolved ; dilute with water, filter, heat nearly to 
boiling, and add barium chlorid. The formation of a fairly 
abundant precipitate of BaS0 4 indicates sulfuric acid. 

Experiment 90. If sulfuric acid has been found, alumina 
is probably also present. To test for this, apply the 
logwood test mentioned in Experiment 95. 

Experiment 91. Another test for aluminum salts in 
baking powders, that may be applied even in the presence 

1 Loc. cit. 



164 SANITARY AND APPLIED CHEMISTRY 

of phosphates, is to burn about 2 g. of the powder 
in a porcelain or platinum dish, extract the ash with 
boiling water, and filter. Add to the filtrate enough 
ammonium chlorid solution so that the mixture shall 
smell distinctly of ammonia. The appearance of a white, 
flocculent precipitate, especially on warming, indicates the 
presence of alumina. The equation is — 

Na 2 Al 2 4 + 2NH 4 C1 + 4 H 2 

= 2A1(0H) 3 + 2NH 4 OH + 2 NaCl. 

Calcium phosphate would be insoluble in the water, 
and alkaline phosphates would be precipitated only when 
alumina was present. 1 

Experiment 92. To test for alum in cream of tartar, add 
to the sample an equal quantity of sodium carbonate, burn 
the mixture, and treat the ash as in the preceding experiment. 

Experiment 92 a. As cream of tartar is often adulter- 
ated with calcium phosphate, to test for this impurity, ignite 
a sample of the cream of tartar and proceed as in Experi- 
ment 88. 

Experiment 93. Ammonium carbonate may be detected in 
a baking powder by mixing it with a little water, and sus- 
pending in the beaker, which should be covered with a 
watch glass, a piece of moistened red litmus paper. After 
a time this will become blue if ammonia is present. 

It is essential that all the ingredients of which a baking 
powder is composed should be well dried before mixing. 
The reason for this is obvious, as without it a partial com- 
bination is liable to take place continuously. Of course 
there is a temptation to add more starch than is essential, 
but an amount of not over 20 to 25 °J is not considered 
excessive, and less than this is sufficient for the purpose. 

1 Leach, 31st Ann. Rep., Mass. State Bd. Health, 1899, p. 638, 



BREAD 165 

An excellent powder for domestic use may be made as fol- 
lows : — 

Lb. 

Cream of tartar, fully dried 1 

Cornstarch \ 

Baking soda \ 

These materials can be bought at a moderate price, and 
should be dried separately and well mixed, and then kept 
in a dry place. 

Experiment 94. To test for lime in a sample of cream of 
tartar, in the absence of phosphates, ignite, dissolve the ash 
in water, with a little HC1, filter, and add an excess of 
ammonium hydroxid, and a few drops of ammonium oxalate. 
The formation of a white precipitate indicates the presence 
of lime (see Experiment 92 a). 

BREAD RAISED BY FERMENTATION 

Raised bread is usually made from wheat or rye flour, 
which is made into a paste with water, salt, and yeast. 
There are several ways in which the ferment may be used. 

(a) The first of these methods is by the use of yeast. 

(&) The second is by the use of " leaven, " or sour dough. 

(c) The third is commonly known as the "salt-rising" 
process. 

In all of these processes, however, the yeast germs 
bring about the fermentation, the only difference, as will be 
seen later, being the source from which the ferment comes. 

A. THE USE OF YEAST 

In the ordinary method the yeast is mixed with a little 
warm ( not hot ) water and flour, or potatoes and salt, and 
thus what is called " sponge " is made. This is allowed to 
rise for some hours, and to it is added more flour, and 
water or milk. Fermentation proceeds, with a continual 



166 SANITARY AND APPLIED CHEMISTRY 

evolution of gas. The gluten which is in the dough 
retards the escape of the carbon dioxid, and the tension of 
the warm gas expands the little cells; then the dough is 
puffed up and becomes light and spongy. It is then 
molded into loaves, and the loaves are set in a warm place 
till the expansion of the gases has raised them somewhat, 
and it is then baked in an oven heated to a temperature of 
from 350° to 570° F. The oven should not be too hot at 
first, as in this case the crust that is formed will prevent 
the interior of the loaf from being fully baked, or it will 
cause the loaf to crack open in an unsightly way from the 
expanding gases. 

Yeast was known to the ancient Egyptians, and from 
them the Greeks and Eomans learned its use. In the 
raising of bread the conditions are favorable first for the 
breaking up of the starch by the diastase of the flour into a 
variety of sugar, and second, by the action of yeast a part 
of the sugar is changed into carbon dioxid gas and alcohol. 
This is represented by the following equations : — 

C 6 H 10 O 5 + H 2 = CeH^Oe ; CqH-^Oq = 2 C 2 H 6 + 2 C0 2 . 

Starch Sugar Alcohol 

Yeast requires for its growth sugar, nitrogenous com- 
pounds, and mineral salts. 

Much time and study has been given, by chemists, to the 
cultivation of pure yeasts, and to the cultivation of those 
varieties best adapted to bread and beer making. The 
variety best adapted to bread-making is said to be Saccharo- 
myces cerevisice. 

Brewers' yeast, which is one of the best to use for 
making bread, should be fresh and not soured. Compressed 
yeast is made from a by-product of the distilleries. " Top 
yeast " or bottom yeast may be used, but the former is 
considered more desirable for bread-making. This mate- 



BREAD 167 

rial is pressed and mixed with 5 or 6 % of starch. It may 
be wrapped in tinfoil, while still somewhat moist, and shipped 
in a refrigerator. 

For domestic use, yeast is prepared by the use of flour, 
water, a little salt, yeast, and some mashed potatoes. To 
this is sometimes added water in which hops have been 
boiled, and the whole is allowed to ferment for about 6 hours. 
This yeast will keep well in a cool place, but in a warm 
place it ferments rapidly and is soon sour. A yeast can 
also be made by preparing a mixture of flour, water, and salt 
and then, without adding the yeast, allowing the germs to 
get in from the air. After a few days, if the mixture is kept 
in a warm place, a product will be obtained similar to the 
material made by the use of yeast. 

Sometimes the yeast plant is mixed with corn meal, and 
the dried mass is put upon the market under the name of 
"yeast cakes." These cakes, which will keep almost in- 
definitely, only need to be soaked in warm water to be ready 
for use. 

B. THE USE OF LEAVEN 

In the use of the leavening, or sour-dough process, which 
has been practiced for hundreds of years, some of the dough 
that has been left over from one batch of bread is used in 
raising the next. "A little leaven leaveneth the whole 
lump." This leaven should be kept in a cool place, lest other 
microorganisms besides yeast plants get into the dough, and 
even then there is often a secondary, or lactic, fermentation, 
so that the resulting bread is sour, or has a disagreeable 
taste. Since compressed yeast cakes are to be purchased 
almost everywhere, this process of raising bread is not used 
as much as formerly. It is chiefly used in the raising of rye 
bread and other coarse forms of breadstuff's. 



168 SANITARY AND APPLIED CHEMISTRY 

C. THE SALT -RISING PROCESS 

The salt-rising process depends on preparing a favorable 
medium in which, the yeast germs will grow, and then 
allowing them to get into the dough from the air, or from 
the ingredients used in making the sponge. The bread 
is started by the use of flour, or corn meal, warm milk, 
and salt. The meal begins to ferment after a short time, 
if kept in a warm place, but the fermented material will 
not have the same taste and odor as the sponge from yeast, 
as various "wild yeasts" are sure to be present. It is 
probable that lactic and butyric fermentation also take 
place to some extent. Although salt, in any quantities 
above 1.4 %, retards alcoholic fermentation, 1 yet as it even to 
a greater extent retards the growth of foreign ferments, such 
as lactic and certain " wild " ferments, it is probable that 
its addition is an advantage, on the whole, if this method 
of fermentation is used. Salt-rising bread is finer grained 
than yeast bread, and has a peculiar and characteristic odor, 
which is due, no doubt, to the lactic fermentation which has 
taken place. 

CAUSES THAT AFFECT FERMENTATION 

Organic acids assist fermentation. 

Mineral acids will destroy the ferment. 

Alkalies stop fermentation. 

Twenty per cent of alcohol stops fermentation. 

Drying does not stop fermentation. 

Boiling destroys the ferment. 

A low temperature hinders fermentation, but does not 
destroy the ferment. 

Alcoholic fermentation takes place best at a temperature 
of from 9° to 25° C. (from 48.2° to 77° F.). The yeast plant 
grows very rapidly, by a process of " budding " ; so that 
1 Jago, " The Science and Art of Bread Making," p. 217. 



BREAD 169 

often one cell will multiply to eighty in 9 hr. Above 
30° C. butyric fermentation sets in, and the products are 
still further changed. Ferments may be kept out of a 
fermentable liquid, or medium, by first sterilizing it by heat, 
then protecting it with a wad of sterilized cotton, or even 
by a capillary tube that is very much twisted. 

If the process of fermentation is allowed to go too far, 
the sugar, or some of it, is further decomposed into lactic 
acid, thus : — 

C 6 H 12 6 = 2 C 3 H 6 3 , 

Lactic acid 

and the dough becomes sour. This may also take place, 
in some cases, by the formation of other acids in the mass, 
as the moist dough is a good medium for the growth of 
various ferments besides the yeast plant. 

Some of the most important things to be noted in the 
making of good bread: — 

1. Thorough kneading, in order to distribute the sponge 
or yeast well through the mass. Lack of attention to this 
will cause the bread to be coarse grained, and to have large 
holes distributed irregularly through it. 

2. The dough should be allowed to rise sufficiently, so 
that the carbon dioxid gas and the alcohol that are formed 
in the process of fermentation may have an opportunity to 
raise the loaf. In this process, the soluble albumen and 
globulin of the flour become insoluble, and can no longer 
be separated from the starch. It is probable that some of 
the gliadin is rendered soluble. The starch is partly 
changed to soluble carbohydrate, and partly changed to 
carbon dioxid and alcohol. 

3. In the process of baking, the heat should not be too 
great, at first, but time should be given for the dough to 
dry throughout the whole mass, for the cell walls to become 
firm, and for the starch to become well cooked. As this 



170 SANITARY AJSTD APPLIED CHEMISTRY 

heating goes on, while the inside of the loaf is not usually- 
heated above 100° C, the outside will gradually get hotter, 
dextrin and some caramel will be formed, and the yeast 
cells will be killed by the heat. Baking renders the starch 
more soluble, and hence digestible. The dextrin that is 
formed is sweeter than starch, and as it is more soluble, 
there is reason in the belief that it is a better food for 
invalids than the crumb. It is also necessary to masticate 
toast thoroughly ; that is, if it is eaten dry, so the process 
of digestion will be further assisted. 

Before putting the loaves into the oven, they are some- 
times moistened on the surface, to assist in the prompt 
formation of a crust that shall restrain the loaf in its ten- 
dency to expand too rapidly. If steam is injected into the 
oven during baking, it produces a glazed surface on the loaf. 
The steam given off from the bread when it is first put into the 
oven acts in the same way. In baking, the heat also expands 
the gases given off, and this assists in puffing up the dough. 

4. The process of fermentation should not be allowed 
to go too far. If we knew the exact amount of lactic 
acid formed in any case, we might add sufficient sodium 
bicarbonate, known as " baking soda," to neutralize it, but 
as we cannot in practice do this, it is better to regulate the 
temperature carefully, so that the dough does not get too 
light. If too much baking soda is added, the loaf will be 
yellow in color, alkaline, and unwholesome. 

In the process of baking, bread will lose from 15 to 
20 % of its weight. This loss is due to the escape of 
carbon dioxid gas, water, and alcohol. Elaborate attempts 
have been made to collect the alcohol that escapes during 
the process, but they have so far been failures. There is 
no small amount lost, however, as Liebig estimated that in 
Germany alone 12,000,000 gal. of alcohol disappeared yearly 
in this industry. There remains in the fresh bread, after 



BREAD 171 

baking, about 2 parts of alcohol per 1000, and after a week 
this amount is diminished to 1 part per 1000. One author 
estimated that 40 2-lb. loaves contained as much alcohol 
as a bottle of port wine. 

A good method for testing the heat of the oven is to throw 
into it some dry flour, and if it soon becomes brown the 
temperature is sufficiently high. The flour should not burn, 
of course, but dextrin should be formed. The question 
naturally arises, Why does not the bread burn at this high 
temperature ? If we remember the large amount of moisture 
and alcohol that are evaporated during the process of bak- 
ing, it is easy to see that for a time, at least, much of the 
heat is used up in driving off these substances, and it is not 
till later in the operation that the temperature is high enough 
to change the starch of the outside of the loaf into dextrin. 

In large bakeries the oven is heated to a temperature a 
little above that required to bake the bread (390°F.) at 
first, and when the bread is put in the temperature falls, on 
account of the amount of cold material that has come into 
the oven, and then gradually rises again, even if no more 
fuel is added. Just before a batch is baked more fuel is 
added, to raise the temperature at the close of the operation, 
and to prepare the oven for the next lot. 

In the old-fashioned way of baking in a brick oven, a fire 
was built in the oven, and, when the bricks became hot, the 
fire was removed, the ashes swept out, and the bread was 
baked with the heat that the walls of the oven had re- 
tained. This method of baking is still used on a large 
scale, especially in England. The Dutch oven, an iron pot, 
with a cast-iron cover, which is kept hot by coals above and 
below, is used for baking where no better appliance is at 
hand. In most large bakeries crackers are baked on the 
swinging shelves of a horizontal cylinder that slowly moves 
above a smokeless fire. About twenty minutes is required 



172 SANITARY AND APPLIED CHEMISTRY 

for baking a batch, which is put into the oven at the same 
point where the previous lot was removed. The swinging 
shelves are so arranged that the heat is uniformly dis- 
tributed under the revolving wheel, and by a mechanical 
arrangement any point of this wheel may be brought in 
front of the charging door. 

That there is a difference between fresh bread and that 
which is several days old is very apparent. What this 
difference is was for some time a question. It was formerly 
said that this difference was due solely to the loss of water, 
but that is proved not to be the case, as there is nearly as 
much water in bread after several days as when the bread 
is fresh, and if stale bread is reheated it becomes for the 
time fresh again. It has been suggested that in fresh 
bread some free water is present, which becomes united 
with the starch or gluten as the bread grows stale, and that 
reheating sets it free again. It has also been stated that 
the difference is only a " molecular one. " Stale bread still 
contains about 45 % of water. The true theory may be 
that as bread dries the fibers gradually approach nearer to 
each other by shrinkage, and the walls of the thousands of 
pores are consolidated, and the size of the pores is thus 
increased. When the stale bread is heated, expansion 
occurs ; by the conversion of some of the water into vapor, 
the adhesion between the fibers is broken up, drawing them 
apart in the direction of the least resistance, producing an 
apparent diminution in the porosity. 

A great impetus was given to the baking industry by the 
Vienna Baking Exhibit at Philadelphia, in 1876. Bread 
furnished by the bakers at present is a better imitation of 
the domestic bread, and hence is more palatable, than that 
formerly made. 

From 100 lb. of flour it is possible to make 135 to 
150 lb. of bread, or, it may be stated, that from f lb. 



BREAD 



173 



of flour it is possible to make 1 lb. of bread. If dry 
flour contains 16 % of water, when this is made into 
bread it gives the composition: flour, 84 parts; water, 16 
and 50, making 150 parts. The water is retained by the 
gluten cells. A flour that contains only a little gluten will 
not make a good strong dough. Bakers take advantage of 
this, and to make a strong dough, that will rise well, they 
mix hard and soft wheat in such proportions as will give 
a dough that is rich in gluten. When considered with 
reference to the amount of gluten, the following analysis of 
bread is of interest: — 

Pee Cent 

Water 40 

Gluten 7 

Starch, sugar, and gum 51 

Salts _2 

100 
From Bulletin 13, Part 9, of the Bureau of Chemistry, 
United States Department of Agriculture, the following 
analyses are quoted : — 





© 




* 
|| 




QQ 


CO 

< 


BSg« 

O E- « S 

PS -< U « 

SitiJ r H 

•< P of* 
O 


Vienna bread 


38.T1 


8.8T 


1.06 


.62 


.57 


1.19 


53.72 


Home-made bread .... 


33.02 


7.94 


1.95 


.24 


.56 


1.05 


56.75 


Graham bread 


34.80 


8.93 


2.03 


1.13 


.69 


1.59 


53.40 


Eye bread 


33.42 


8.63 


.66 


.62 


1.00 


1.84 


56.21 


Miscellaneous bread . . . 


34.41 


7.60 


1.48 


.30 


.49 


1.00 


56.18 


Biscuits or crackers. . . . 


7.13 


10.34 


8.67 


.47 


.99 


1.57 


73.17 


Rolls 


2T.98 


8.20 


3.41 


.60 


.69 


1.31 


59.82 



Contrary to the opinion that has been held, recent analyses 
show that white bread really contains more proteids, espe- 
cially those that can be absorbed, than " whole meal " or 
Graham bread. 



174 



SANITARY AND APPLIED CHEMISTRY 



For comparing the " crumb" and the "crust," we have 
the following analyses, calculated from anhydrous bread: — 







Nitroge- 
nous 


Dextrin 
and Sol. 
Starch 


Sugar 


Fat 


Starch 


Water in 
Original 
Bread 


Crumb . . 
Crust . . . 


11.29 
10.97 


14.97 
16.09 


4.17 
4.15 


1.68 
.71 


67.87 
68.07 


40.60 
13.00 





A great variety of products is now put on the market 
by the cracker factories. These include such brands as 
"pilots," made without yeast, but with hot water, lard, flour, 
and salt ; " sodas," made by the use of flour, yeast, and lard, 
or cotton-seed oil ; "wafers," made by the use of butter, sugar, 
vanilla, flour, and baking powder ; and " snaps," made from 
sugar, flour, lard, baking powder, and ginger. 

Starch alone is not sufficient to sustain life, for the nitro- 
gen, to assist in building up the tissues of the body, must 
also be obtained from some organic source. One fact not 
to be lost sight of is that man does not live "by bread 
alone." He does make use of a large amount of nitrogenous 
food, in the shape of beef, milk, eggs, etc. ; so it is not ab- 
solutely necessary that the wheat or other grain should 
furnish sufficient nitrogenous material to sustain life. In the 
modern processes of milling, the first and second grades of 
flour are really rich in proteids. The bran that man may 
have discarded is used by the lower animals for food, and so 
in the beef, pork, and mutton we get the proteids that are 
necessary. Man chooses to allow the animal to do this 
concentrating for him, and thus he has the advantage of a 
mixed diet. 

Some so-called Infants' Foods are principally starch, and 
when fed to infants are practically useless, as the starch- 



BREAD 175 

converting ferments of the pancreatic juice are not secreted 
till about the end of the first year. 1 

Bread must, however, be regarded as one of the most 
nutritious of foods. It yields to the blood a large quantity 
of carbohydrates, considerable proteids and mineral salts, 
and but very little fat. When it is eaten with butter, the 
deficiency of fat is made up ; we also eat bread with meat, 
and thus the lack of proteids, which would be necessary to 
make bread a perfect food, is supplied. Bread and milk is 
a better balanced ration than bread alone, as the milk fur- 
nishes both proteid and fat to supplement the deficiency. 

Many experiments have been made, and much has been 
written, on the relative value of white bread and bran, Gra- 
ham, and whole-wheat bread. Even if sometimes the whole- 
wheat bread does contain more proteids, they are in such a 
form that they cannot be readily acted upon by the diges- 
tive juices and so there seems to be a less absorption of 
them than in the case of white bread. Artificial digestion 
experiments confirm this opinion. 2 Then, too, the coarser 
breads are liable to produce some irritation in the intes- 
tines, and this prevents perfect digestion and absorption of 
the food. 

Many attempts have been made to perfect a flour, richer 
in proteids, and better adapted than ordinary flour to sustain 
animal life. Such attempts are the mixing of pease meal 
and of casein with flour, and the use of milk in making 
the bread. There are also many so-called " germ flours " on 
the market, and if it is proved that they are well absorbed, 
this may help to solve the problem. 

It is probably true that the second grade of flour will 
make a more nutritious bread than the highest " patent." 
If stale bread is rebaked, it becomes, for the time, fresh 

1 Cotton's " Anatomy, Physiology, and Hygiene of Childhood." 

2 Snyder, U. S. Dept. Agric, 0. Ex. Sta., Bui. 101. 



176 SANITARY AND APPLIED CHEMISTRY 

again. It is a well-known fact that stale bread has the 
reputation of being more wholesome, and this is founded on 
reason, because fresh bread has a tendency, when masti- 
cated, to roll together in doughy masses that are not 
readily attacked by the digestive fluids. Stale bread retains 
its porosity, to a large extent, while it is being mixed with 
the saliva. 

In addition to wheat bread, a brown bread, made from 
wheat and Indian meal, or rye and Indian meal, is much in 
favor in some localities. The addition of rye or wheat 
assists very much in the raising of the dough, because there 
is not sufficient gluten in the meal to make a strong dough 
that will retain the gas bubbles. The properties of flour 
from the other grains are discussed elsewhere. 

Bread may be bad from several causes. Among these 
may be mentioned the following : — 

1. It is bitter, from an abnormal growth in the flour, or 
from the grain being partly spoiled. 

2. It is heavy, from being imperfectly baked, or from the 
use of poor yeast, or from not being allowed to rise suffi- 
ciently before being placed in the oven. 

3. The flour may be deficient in gluten, from bad milling, 
or from the " growing " of the wheat before it was ground. 
In this case light bread cannot be made, as the dough does 
not possess sufficient tenacity to cling together and hold 
the gases that are evolved. 

4. The bread may be sour from overfermentation, or, 
what amounts to the same thing, from allowing the fer- 
mentation to proceed at too high a temperature. There is 
no excuse for this, as it simply denotes carelessness or 
ignorance. 

5. Bread may be moldy if it is kept in a damp place or 
if it is kept too long. This mold is due to the growth 
of microscopic plants that find the moist bread a fertile 



BREAD 177 

medium. These molds may be white, green, orange, or black. 
They are supposed by some to be poisonous and to produce 
severe disorders, but even if that is not the case they 
render the bread unfit for use. 

The center of a loaf of bread is sometimes the feeding 
ground for these lower organisms, especially in very warm 
weather, because the heat of the oven has not been sufficient 
to entirely sterilize the interior, and so the bread spoils. The 
texture of the loaf will be changed so that it will be stringy 
and a disagreeable odor is emitted. 

6. The bread may be of a dark color, though not made 
from lower grades of flour. This is due to the change that 
has taken place in the grain or in the flour by its being wet 
and allowing the starch to change to dextrin, gum, or sugar. 
This is practically what takes place in the malting of grains. 

ADULTERATION OF FLOUR AND BREAD ; COMPOUND 

FLOUR 

The most common adulteration of flour in the United 
States is the addition to it of other flours, especially that 
of corn and possibly rice. This can be readily detected by 
the use of the microscope. The government requires all 
such flours to be labeled " Compound, " and to pay a reve- 
nue tax of 4 cents per barrel. 

As white bread commands a better price than dark, and 
as there is always a greater demand for white bread, various 
attempts have been made to make a white bread from a low 
grade of flour. Substances used for this purpose formerly 
constituted the chief adulteration to which flour was liable. 
In Europe copper sulfate and alum have been used, but in 
many countries their use is now prohibited by law. Even 
so small a quantity as 1 part of copper sulfate in 10,000 parts 
of flour is said to be sufficient to enable the baker to make 



178 SANITARY AND APPLIED CHEMISTRY 

a white bread from a low grade of flour. The use of this 
chemical is condemned on account of the poisonous nature 
of the salts of copper. 

Liebig states that the alum makes insoluble the gluten that 
has before been rendered partially soluble by the acetic and 
lactic acids that were developed in the process of fermenta- 
tion. In this way the change from starch to dextrin or 
sugar is arrested. There is a difference of opinion as to the 
effect of alum upon the system, but the most reliable testi- 
mony is that as the loaf is not heated much above 100° C. 
the alumina will not be rendered insoluble. In that case it 
will go into the circulation and thus tend to injure the sys- 
tem. The amount of alum used is not over 1^ to 3 ounces 
to 100 lb. of flour. It is stated that by the use of a patent 
process some oxid of nitrogen is now used in bleaching flour. 

Experiment 94 a. To test for copper sulfate some of the 
bread may be ignited in a porcelain dish with nitric acid, 
and the ash that is left is boiled with a few drops of nitric 
acid, diluted and filtered. To one half of the filtrate an 
excess of ammonium hydroxid is added, and a blue colora- 
tion will indicate the presence of copper. The other half 
should be neutralized with sodium hydroxid, made slightly 
acid with acetic acid, and tested by means of potassium f erro- 
cyanid. The appearance of a reddish color indicates copper. 

Experiment 95. To detect alum in flour, the logwood test 
has been found very satisfactory. Fifty grams of flour are 
mixed with 50 cc. of distilled water, and to this is added 
5 cc. of a freshly prepared logwood solution, and the whole 
is made alkaline with 5 cc. of a solution of ammonium 
carbonate. With as small a quantity of alum as 10 ^ o0 the 
color of the solution will be lavender blue, instead of a dirty 
pink. It is well to set the mixture aside in a warm place for 
2 hr., and notice if the blue color is permanent. 



BREAD 179 

Experiment 96. To test for alum in bread, add to 50 cc. 
of water 5 cc. of the logwood solution and 5 cc. of am- 
monium carbonate solution. Soak about 10 g. of the crumb 
in this for 5 minutes, pour out the liquid, and dry the bread 
at a gentle heat. If alum is present the lavender or dark blue 
color will appear, but if the bread is pure it will turn to a 
dirty brown color. 

As alum is not often used in flour in this country, these 
tests may be made with some of the " self -rising " flours, 
which are liable to contain alum, or upon cakes made from 
this flour. 

Ergot is sometimes found in flour, especially in that made 
from rye. This is due to the " spurred rye, " as it is called, 
or really to a fungus growth that is found on the grain. It 
is poisonous, and sometimes has proven injurious to the 
lower animals. 

There is very little danger, in the United States at least, 
of the adulteration of flour with clay, chalk, terra alba, or 
any such materials. 



CHAPTER XIII 

PREDIGESTED AND SPECIAL FOODS 

Breakfast foods and " predigested " foods have recently 
been introduced, ostensibly to take the place of foods 
improperly prepared, and to assist digestion. That there 
is a popular demand for foods of this kind there is no doubt, 
but their extended use is only another illustration of the 
tendency in the United States to allow some one else to do 
the work of the household for us, even though the food thus 
prepared may be expensive and unsatisfactory. The state- 
ments made on the package usually have nothing to do 
with the value or digestibility of the food. The price at 
which they are sold also bears no relation to the weight of 
the package or the nutritive value. 

Foods for infants and invalids are made up largely of 
cereals which are modified by application of heat, by digestion 
with malt or diastase, and by malting the cereal, adding cream 
or milk, and evaporating. Among those prepared by heat 
alone may be mentioned Blair's and Imperial Granum ; Mel- 
lin's and Horlick's foods are representatives of the class 
that is made by mixing wheat flour with malt and a little 
potassium carbonate, moistening with water and heating at a 
fixed temperature for several hours. 1 The starch of the flour 
is by this process changed to maltose and dextrin, which are 
soluble substances. In making the malted cream foods, the 

1 Canadian Dept. of Inland Rev. , Bui. 59. 
180 



PREDIGESTED AND SPECIAL FOODS 



181 



flour is made into dough, baked, ground, and malted, mixed 
with cream, and evaporated to dryness in a vacuum. Foods 
of this class, such as Malted Milk and Nestle's Food, are 
richer in fat and albumen than the others mentioned. 1 

The following analyses from Kdnig illustrate the differ- 
ence in composition between some of these foods : — 





Water 


Albumen 


Fat 


Carbohydrates 






Sugar 


Starch 


Ash 


Nestle's, .... 
Horlick's .... 
Neave's .... 


6.15 
5.08 
4.27 


9.91 
9.67 
13.20 


4.46 
.34 

1.70 


43.30 
66.39 
4.71 


35.00 
16.00 
74.14 


1.74 
2.02 
1.09 



In discussing the popular " breakfast foods " a prominent 
writer says : — 

" This craving for something new to stimulate a jaded ap- 
petite, already spoiled by endless variety and bad combi- 
nations, has led to the manufacture of a cereal preparation 
for nearly every day in the year. No better comment on the 
laziness or willful ignorance of the American providers could 
be made than this. Little do the people know about wheat 
or cooking if they suppose that grain can be changed by 
manipulation in any kind of machine so as to give a greater 
food value than was contained in the grain. While it 
is true that some of these preparations are far better than 
the half-cooked grains found on so many tables, the fact re- 
mains that it is the cook and not the substance which is 
poor. It is not always best to have food that is too easily 
digested." 

"Apredigested food is quickly absorbed into the circulation, 

1 " Davis's Chemistry for Schools," p. 285, from Konig. 



182 



SANITARY AND APPLIED CHEMISTRY 



and hence a small quantity causes a sensation of fullness 
and satisfaction, which, however, soon passes away and faint- 
ness results. This is especially true of the sugars and the 
dextrins. Frequent meals should go with these easily ab- 
sorbed foods. This rapid digestion is the cause of much 
pernicious eating of sweets between meals, which satisfies 
the appetite for the time being and prevents substantial 
quantities of other foods being taken at the time when they 
are offered." * 

It is well to note that the oatmeal sold in bulk is practi- 
cally the same as that sold in packages, only the latter has 
been better protected from vermin and dust. It is true 
that oatmeal contains more protein and fat, and as far as 
the analysis shows, offers a better-balanced ration than most 
of the other foods, but that does not prove that it should be 
used exclusively as a breakfast food. The cereals — wheat, 
barley, corn, and oats — are the chief source for the manu- 
facture of all these foods, but they are prepared by different 
processes. 

The analysis of a few typical brands is as follows : 2 — 



Grape Nuts 

Malta- Vita . ... 
F. S. Boiled Avena . . 
Ealston's Health Break- 
fast Food ..... 
Pillsbury's Vitos . . . 
Pettijohn's Breakfast Food 
Quaker Rolled Oats . . 
Shredded Whole Wheat . 
Vigor 



W 

I 

so 

8 


H 5 


O0 

3g 


m 
En 

< 


P5 

8 

s 

K 
Q 
U 
M 
O 


M 

00 


8.00 


12.73 


73.78 


1.57 


2.02 


1.90 


8.93 


11.84 


73.19 


1.55 


1.82 


2.67 


9.68 


18.42 


60.85 


6.88 


2.22 


1.95 


11.07 


12.55 


72.11 


1.72 


1.35 


1.20 


11.19 


13.08 


73.44 


1.08 


.58 


.58 


10.43 


12.11 


71.08 


2.50 


2.30 


1.58 


9.40 


17.55 


61.56 


7.20 


2.40 


1.89 


8.91 


11.32 


73.93 


0.87 


3.40 


1.57 


9.12 


14.46 


69.18 


1.65 


2.38 


3.21 



Hisn 

WW 



$ .13 
.11 
.07* 

.07| 

.07 

.07 

.05 

.11 

.15 



1 Richards and Woodman, " Air, Water, and Food," p. 156. 

2 Slosson, Wyoming Exp. Station, Bui. 33. 



PREDIGESTED AND SPECIAL FOODS 183 

From a study of the analysis of a large number of these 
foods, F. W. Robison * arrives at these conclusions : — 

"1. The breakfast foods are legitimate and valuable 
foods. 

"2. Predigestion has been carried on in the majority of 
them to a limited degree only. 

" 3. The price for which they are sold is, as a rule, 
excessive and not in keeping with their nutritive values. 

"4. They contain, as a rule, considerable fiber, which, 
while probably rendering them less digestible, at the same 
time may render them more wholesome to the average 
person. 

" 5. The claims made for many of them are not warranted 
by the facts. 

" 6. The claim that they are far more nutritious than the 
wheat and grains from which they are made is not sub- 
stantiated. 

"7. They are palatable, as a rule, and pleasing to the 
eye. 

"8. The digestibility of these products, as compared 
with highly milled foods, while probably favorable to the 
latter, does not give due credit to the former, because of 
the healthful influence of the fiber and mineral matter in 
the breakfast foods. 

" 9. Rolled oats, or oatmeal, as a source of protein and of 
fuel is ahead of the wheat preparations, excepting, of 
course, the special gluten foods, which are manifestly in a 
different class. w 

Macaroni, vermicelli, and spaghetti are made in Italy, 
France, and Switzerland, from certain highly nitrogenous 
varieties of wheat. They have been more recently made in 
this country. The macaroni is made by mixing " semolina " 

1 Robison, Michigan Agric. Exp. Station, Div. Chem., 1904. 



184 



SANITARY AND APPLIED CHEMISTRY 



— the hard, flinty part of the wheat grain — with the special 
wheat, making it into a paste, and pressing through the 
bottom of a cylinder pierced with holes. The tubes which 
come through the perforations are cooled, cut in lengths, 
and dried on screens. 

The composition of macaroni, according to Church, 1 is : — 





Fine 
Variety 


Cheaper 
Variety 


Water 


13.0 

11.1 

73.8 

.9 

.4 

.8 


10.0 


Albuminoids, &c 

Starch, &c 

Fat 


13.5 

70.8 

2.3 


Cellulose 


1.4 


Mineral Matter 


2.0 







Macaroni should be well soaked in water before cooking, 
and may very conveniently be served with cheese, which 
adds to its nutritive value. Sir Henry Thompson, 2 in 
speaking of macaroni, says that " weight for weight it may 
be regarded as not less valuable for flesh-making purposes 
in the animal economy than beef or mutton. Most people 
can digest it more easily and rapidly than meat. It offers, 
therefore, an admirable substitute for meat, particularly for 
lunch or the midday meal/' 

1 Church, " Food, " p. 81. 

2 Quoted from W. G. Thompson, ''Practical Dietetics," p. 152. 



CHAPTER XIV 
SUGAES 

History and Classification of Sugars. Sugar was known 
at such an early age that the date of its discovery is lost. 
We hear of its use in India perhaps earlier than elsewhere. 
In Europe honey was used for sweetening purposes before 
sugar came into general use. The sugar cane was culti- 
vated in the regions adjoining the Mediterranean Sea as 
early as 1148, in the West Indies in 1506, and on the North 
American continent in 1800. Sugar was first noticed as a 
curiosity, then it came into use as a medicine, and finally 
has become a necessary part of our diet. Sugar was at first 
confounded with manna, and was supposed to be the dried 
juice of a plant. As it was not well understood, physicians 
regarded it as having an injurious effect upon the system. 
Honey was thought to be more wholesome, because a 
" natural food." We find the price of sugar quoted at 45 cents 
per lb. when it first came into use. The amount of sugar 
used in civilized countries is constantly on the increase. 

The sugars have essentially the same food value as the 
starches, as the latter must be converted into dextrin or 
sugar in the process of digestion. As cane sugar must be 
changed into a form of grape sugar before being digested, 
the latter is often spoken of as a " predigested w form of 
food. Although sugar is an excellent energy producer, and 
in fact stands at the head of the list, yet an overindulgence 
in this food, especially in cane sugar, is sure to cause 
flatulent dyspepsia and other disorders. 

185 



186 SANITARY AND APPLIED CHEMISTRY 

About 8,000,000 tons of sugar are consumed annually 
in the world, and English-speaking nations consume the 
most per capita. In 1895 the per capita consumption in 
England was 86 lb. ; in Germany, France, and Holland, 
30 lb. ; in Italy, Greece, and Turkey only 7 lb. ; and in the 
United States, 66 lb. 1 The per capita use of sugar in 1903 
in the United States was 71.1 lb. 

On account of their importance as food materials sugars 
should be thoroughly discussed, and their composition and 
relations to other nutrients should be well understood. In 
general the sugars are recognized by the fact that they are 
readily soluble in water ; that they have a sweet taste ; and 
that they rotate the plane of polarized light. 

There are a large number of sugars known to the chemist, 
but up to the present time the property of sweetness has not 
been identified as belonging to any definite molecule or to 
any definite combination. In addition to the sugars, there 
are other substances that are sweet, as, for instance, the alco- 
hols and the organic compound Saccharin, CyHsC^SN, which 
was recently discovered. This is about 500 times as sweet 
as cane sugar. The addition of one part of saccharin to 1000 
parts of glucose renders the latter as sweet as cane sugar. 
Saccharin is sometimes used to replace sugar for diabetic 
patients, but it has no food value. 

The sugars that are in common use may be divided into 
two general classes: the sucrose, or cane sugar, group, 
having the composition C 12 H 22 0i 1 , and the glucoses, or 
grape sugars, having the composition CeH^Og. Sugars of 
both these classes are found under various names in a large 
number of food substances. These two groups are also 
very intimately related, so that by " inversion," with heat 
and dilute acids, some of the members of the first group 
may be changed to those of the second group. 

1 Mary Hinman Abel. (Thompson, p. 128.) 



SUGARS 187 

SUCROSE, C12H22O11 

The most important members of this group are sucrose, 
maltose, and lactose. Sucrose, or cane sugar, occurs abun- 
dantly in roots, grasses, and stems of many plants, as well 
as in fruits. There are, however, only a few plants from 
which it is economical to make sugar. These plants are the 
sugar cane, the sugar beet, sorghum, the maple and birch 
trees, cornstalks, carrots, and sweet potatoes. About two 
thirds of the sugar, as estimated by Wiley, is made from 
the beet, and one third from sugar cane. The other sources 
are of so little importance that they need only be mentioned 
incidentally. Sugar obtained from either sugar cane, the 
beet, or any other of the sources mentioned has the same 
composition, and the chemist cannot recognize any differ- 
ence between the products. 

From 13% to 20% of sugar is found in the stalks of sugar 
cane; from 4% to 15% in the sugar beet; sometimes as much 
as 15% in sorghum; and the sap of the maple tree contains 
a little over 2% of sugar. 

SUGAR CANE 

Sugar cane belongs to the family of grasses, of which 
there are many varieties growing in tropical and subtropical 
countries, especially in the moist climate of islands and the 
sea coast. The sugar cane is successfully cultivated mainly 
in Cuba, the West Indies, Louisiana, the Philippines, 
Java, Brazil, and the Hawaiian Islands. The cane flourishes 
best where the mean temperature is from 75° to 77° F., but 
it grows fairly well where the mean temperature is not be- 
low 66° F. Sugar cane is propagated not by seeds, but by 
cuttings. The young cane sprouts from the roots each year, 
and in the United States usually three crops are gathered 
from one setting, so on each plantation one third of the space 



188 SANITARY AND APPLIED CHEMISTRY 

is set with, new cuttings each year. In the West Indies, how- 
ever, the sprouts that come from the old roots are cut for a 
series of years till at last the plants die, and are then replaced 
by fresh cuttings. There are two processes of extracting 
the juice from the sugar-bearing material. The first is by 
crushing in roller mills and the second is by diffusion. The 
former process has been used more especially for making 
sugar from cane and the latter from the sugar beet. 

MAKING SUGAR FROM SUGAR CANE 

The average analysis of the ripe cane shows it to contain 
of sugar 18%, fiber 9. 5%, water 71%; but the juice contains 
of sucrose 18%, glucose .30%, gums 1.40%, mineral salts 
.30%, water 80 %. 1 By the best practice about 84% of the 
juice is extracted. 

The cane is cut in the fall, and after being stripped and 
topped is passed through a " shredder," to tear it to 
pieces, then several times between heavy horizontal rollers, 
to extract the juice. The " begasse " or crushed cane left 
after pressing is burned as fuel under the boilers. The juice 
in Louisiana does not often contain over 14% of sucrose, but 
in Cuba it may run as high as 18%. The juice is passed 
through a screen to remove suspended matter, then nearly 
neutralized with milk of lime, and heated to coagulate the 
albumen. This is called " defecation." The lime not only 
neutralizes the acid, which is quickly formed, and thus pre- 
vents it from "inverting" the sugar, or changing it to 
uncrystallizable sugar, but it unites with the nitrogenous 
matter and causes it to separate. The scum, which contains 
many of the impurities, is allowed to rise to the surface and 
is then filtered off and pressed to remove as much of the 
saccharine liquid as possible. The pressed filter cake may 

1 Thorp, " Outlines of Industrial Chemistry," p. 388. 



SUGAKS 189 

be used as a fertilizer. The juice is often treated with sul- 
furous acid, which is made by burning sulfur, to prevent 
fermentation and improve the color. The juice must, how- 
ever, be left slightly alkaline to prevent inversion. The 
juice may also be filtered through bone black or animal 
charcoal in order to remove the color, but this is not often 
practiced at the present time in the United States. 

Formerly the saccharine liquid was evaporated in open 
pans, until it began to crystallize, then emptied into shallow 
tanks and stirred till it was cool. The mixture, which con- 
tained both molasses and sugar, was placed in hogsheads 
having holes bored in the end, so that the molasses could 
drain out. By this process a sugar called " muscovado " was 
produced, which contained from 87 to 90% of sucrose. The 
molasses obtained in this way was of good quality, but the 
process was not economical, as so much of the sugar was 
" inverted " in boiling. 

In the modern sugarhouse the juice is first concentrated 
in "triple-effect" evaporators, which utilize the steam given 
off from one pan to assist in heating the next, and are there- 
fore very economical ; then the juice, which in this way is 
much concentrated, is run into the vacuum or " strike " pan. 
Usually the entire system of evaporation is heated by 
exhaust steam, and this conduces greatly to the economy of 
the process. 

In the vacuum pan the juice is heated by steam coils and 
the vapor is pumped off, thus reducing the pressure so that 
the sirup will boil at 150° to 180° F. instead of 230° to 
250° F., which would be the case in the open pan. After 
the sugar has boiled to " grain," or till it begins to crys- 
tallize, some more sirup is admitted to the pan and crystals 
of sugar are gradually "built up" till a sufficiently large 
charge is obtained. A vacuum is maintained on the pan 
during the entire operation. 



190 SANITARY AND APPLIED CHEMISTRY 

The mixture of molasses and sugar which is then drawn out 
of the vacuum pan is called masse cuite. A part of it is run 
directly into the " centrifugals/' and the rest into a " mixer," 
where it is constantly stirred by mechanical means, until 
there is an opportunity to run it into the centrifugals. The 
latter revolve on a perpendicular axis at the rate of about 
1200 times per minute. The outside or perpendicular wall 
of the drum is perforated, and by the rapid rotation the 
sirup " flies off " into the space outside the drum and runs 
into a receptacle below. The top of the drum is open to 
facilitate charging and washing, and the charge can be 
dropped out at the bottom, when the sirup has been separated 
from the sugar. The sugar while in the centrifugal may 
be washed by throwing into it while running a small 
quantity of water or a saturated solution of pure cane sugar. 

The liquid that has run through the centrifugal together 
with the washing is diluted, defecated, and again boiled down, 
forming a second masse cuite, from which a " second sugar " 
is obtained, and the process is sometimes repeated to obtain 
a third or even a fourth masse cuite. The second sugar is 
often mixed with the concentrated juice before it is run into 
the vacuum pan, to save time in " building up " the grain of 
the sugar. The impure molasses finally obtained is run 
into a cistern and worked up later in the season in various 
ways. Eecently it has been found to be economical to mix 
some of this molasses with the feed of the mules which are 
employed on the plantation. 

The object of the sugar boiler is to obtain as large a quan- 
tity of cane sugar, and as little uncrystallizable or " invert " 
sugar as possible, since the impure molasses is of little 
commercial value. 

The total production of sugar from the sugar cane in the 
United States in 1903 was 292,800 tons. x 

1 Dep. of Com. and Labor; Statistical Abstract of the U.S. for 
1903. 



SUGARS 191 



MAKING SUGAR FROM THE SUGAR BEET 

It was in 1747 that Marggraf, a German chemist, an- 
nounced that it was possible to obtain a sugar from beet 
juice which was identical with that obtained from the 
sugar cane. Achard, a pupil of his, actually erected a 
factory and made some beet sugar, but, as only 2 or 3% of 
sugar could be extracted from the beets, it was not a com- 
mercial success. Napoleon I, in 1806, caused a bounty to 
be offered for beet sugar, and thus the manufacture was 
greatly stimulated. At first the beet contained only 6% of 
sugar, but it has been improved so much by cultivation that 
it now often contains as high as 15%. The other constituents 
of beet juice embarrassed the sugar boiler greatly for some 
time, but the process of manufacture has been so much im- 
proved that now these very impurities have been made a 
source of profit. 

Although several methods have been used for extracting 
sugar from the beet, the " diffusion " process has been the 
most successful. According to the German method, the 
beets are cut into fine chips, and are then put into a series 
of large iron vessels, where they are extracted with warm 
water. The " battery " of diffusors is so arranged that the 
sweet water, heated to 60° C, may be circulated from one 
vessel to another, till the sugar is practically all removed 
from the chips. These are then dropped out of the cylinder. 
It is again filled with fresh chips, and so connected as to be 
made the last of the series of diffusors through which the 
juice is circulating. The exhausted chips are used as cattle 
food, as they are rich in nitrogenous matter. After the 
water has remained in contact with one lot of material for 
20 minutes, it is drawn through a juice warmer before it is 
brought into the next diffusor. Although considerable water 
is used in this process, and the juice must be concentrated 



192 SANITARY AND APPLIED CHEMISTRY 

somewhat more than when extracted by crushing, yet the 
juice is so much more free from foreign nitrogenous sub- 
stances that the diffusion process can be used with greater 
economy and success. All but 0.5% of the sugar is ex- 
tracted. 1 

The crude juice, which contains about as much sugar as 
the original beet juice, is heated to coagulate the albuminoids, 
and then lime is added to saturate the free acids, and assist 
in throwing down organic matter. Carbon dioxid gas is made 
to pass through the solution, and the latter is then forced 
through the filter press. Sometimes this operation of "car- 
bonation" is repeated. Then the juice usually goes to the bone- 
black filters. Sometimes the treatment with lime and carbon 
dioxid gas, and sulfurous acids, purifies the juice so that no 
subsequent treatment with bone black is necessary. Special 
care and treatment is required to make from the sugar beet a 
fine crystalline sugar which has no unpleasant taste or odor. 

The molasses obtained by this process is boiled down 
for a second sugar and a second molasses. As the latter 
contains about 40% of sugar that cannot be crystallized, this 
is usually recovered by treating with quicklime to form a 
tricalcium stearate, C 12 H 2 20 U ,3 CaO. This latter salt is filter- 
pressed to separate the precipitate from the sirup and im- 
purities, and this precipitate is used instead of lime in the 
defecation of fresh juice, or it may be decomposed by passing 
carbon dioxid into it. In 1903, 247,563 tons of beet sugar 
were made in the United States. 

MAPLE SUGAR 

The manufacture of sugar from the sap of the hard 
maple, Acer saccharinum, is quite common in the extreme 
Northern states and in Canada. The sugar season is 
limited to 6 or 8 weeks in the spring. The sap is drawn 
from the trees by "tapping," or making an incision 

1 Thorp, " Outlines of Industrial Chemistry," p. 393. 



SUGARS 193 

through the bark, and arranging a spout to carry the juice 
to a receptacle below. This sap is then concentrated in 
shallow pans over an open fire, skimmed, and strained. 
Good sirup contains about 62% of cane sugar, with 
varying amounts of invert sugar. Maple sugar contains 
about 83% of cane sugar. 

On account of the agreeable taste, which is due to certain 
characteristic substances, the maple products always com- 
mand a high price in the market. There is therefore a 
temptation to imitate these products, or adulterate them. 
Brown sugar, especially, is often melted with inferior maple 
sugar, while maple sirup is adulterated with glucose, molasses, 
or refined sugar. Hickory bark is said to be used as a 
flavoring material in the imitation maple sugars. It is not 
difficult for the experienced chemist to detect the spurious 
article. In 1903, 5150 tons of maple sugar were made in 
the United States. 

The manufacturers of adulterated maple sirups go so far 
as to put upon the package a guarantee that they are not 
adulterated, and do not contain glucose, corn sirup, or 
grape sugar ; but they omit to state that they consist wholly 
of cane sugar, with a little coloring matter and flavoring 
material. The substances used may not be injurious, but 
there is, nevertheless, a fraud upon the consumer in the 
price he is charged for an article which is not what it 
purports to be from the label. 

SORGHUM SUGAR 

The juice of the sorghum (Andropogon sorghum ) has been 
used for a long time in the United States by the farmers as 
a source of a cheap sirup, and the United States Depart- 
ment of Agriculture at one time carried on very extensive 
experiments, looking to the possibility of making a crystal- 
lizable sugar from sorghum. The cane has been improved so 



194 SANITARY AND APPLIED CHEMISTRY 

that it often contains 15% of sugar. Many of the difficul- 
ties have been overcome by the use of the " diffusion pro- 
cess" and improved methods of purification of the juice. 
Although a good quality of sugar can be made, yet the 
manufacture can hardly be called a commercial success, and 
practically no sugar is made from sorghum. Much of the 
so-called sorghum sirup which is on the market is a mix- 
ture of sorghum and glucose. 

MOLASSES 

Molasses is of various grades, and contains the uncrys- 
tallizable sugar, some cane sugar, gum, coloring matter, 
and mineral salts. Where the drippings from the 
vessel from which the " first" sugar crystallizes are 
used as molasses, we have a very pure product. Since 
the lower grades of sugar are made by evaporation of the 
drippings and washings of the several crystallizations, they 
contain more impurities and more moisture than does 
granulated sugar, and it is a question whether they are 
really cheaper. It is probably on account of its ready 
solubility in the mouth that we get the impression that the 
impure sugar is sweeter. 

SUGAR REFINING 

Since much of the sugar raised on the plantations is put 
on the market in its " raw M condition, it must be refined or 
purified before it is fit for use. Sugar refineries are usually 
situated in the large commercial centers, in this country 
at New York, Philadelphia, ISTew Orleans, and San Francisco. 
The buildings are very high, so that advantage can be taken 
of gravity in handling the product. The raw sugar is par- 
tially dissolved in molasses in large vats, or "melters," 
placed below the floor of the basement. The masse cuite 
thus formed is run directly into the centrifugals, where it is 



SUGARS 195 

washed slightly. The sugar thus obtained is "melted" in 
warm water, strained from the coarser particles of dirt, and 
pumped to the top of the building. 

The solution may be " defecated " by boiling with lime, 
clay, alum, calcium phosphates, or with fresh blood from 
the packing house. It is then conveyed to "bag filters," 
made of heavy cotton twill, from 5 to 8 ft. long. Here 
the refuse that would not settle in the defecating tanks 
is collected. The liquor, which is now clear, but of a 
brownish color, is run into the " bone-black filters." These 
filters are long cylinders, often extending through several 
stories, fitted with a perforated bottom over which a blanket 
is spread, to prevent the bone black, with which the cylinder 
is filled, from falling through. 

The sugar solution is allowed to trickle slowly on to this 
filter, and to remain for about 24 hours in contact with the 
bone black ; the product first drawn off is the purest. 
When the bone black is exhausted, it is washed with water, 
which, of course, is saved, and the bone black is " revivified " 
by being burned in closed retorts. The bone black, when it 
is cold, is sifted and the dust is sold for the manufacture of 
fertilizers. 

The colorless liquor is then ready to be concentrated in the 
"vacuum pan" previously described (p. 184). When the 
masse cuite has crystallized sufficiently to make " loaf sugar," 
it is run into conical sheet-iron molds having an open- 
ing at the bottom, and the sirup runs off. Then a satu- 
rated solution of sugar is poured on the top of the " sugar 
loaves " to wash out the uncrystallized material. This pro- 
cess of drainage and drying may, however, be much short- 
ened by placing several cones at a time in a centrifugal, 
and " throwing out " the sirup by rapid rotation. 

Experiment 97. To show the action of bone black, dissolve 
about 30 g. of brown sugar in warm water, add at least 25 g. 



196 SANITARY AND APPLIED CHEMISTRY 

of bone black, and after shaking the mixture for some time, 
filter. A colorless filtrate should be obtained. The operation 
may be repeated with the filtrate if it is not colorless. 

GRANULATED SUGAR 

To make granulated sugar directly, the mixture of sugar 
and sirup, frequently 3500 pounds in a charge, is drawn 
off from the vacuum pan into a mixer, where it is stirred 
while cooling to prevent the grains from sticking together. 
The sugar and sirup are separated in the centrifugal, as in the 
case of making raw sugar, and the sugar is washed with fresh 
water. It is then conveyed to the " granulator," which is a 
rotating cylinder, set at a slight incline, and heated by steam. 
Here the sugar, which enters the upper end, is dried, and the 
grains are separated one from another, and then pass through 
a series of sieves, and are finally run into barrels for ship- 
ment. The sirups obtained in the refining process maybe 
again filtered through bone black, and boiled to make lower 
grades of sugar, or they may be mixed with glucose and put 
on the market directly as table sirups. 

To make the granulated sugar from loaf sugar, the cones 
are crushed and sifted, and the crystals passed over a heated 
table into the packing barrels. Usually a little " ultra- 
marine " is added to the sugar to correct the slight yellow 
color. Although this coloring matter is not injurious, yet 
in some manufacturing processes it will be found to give a 
disagreeable odor to the sirup, on account of the decomposi- 
tion of ultramarine by acids. 

Powdered or pulverized sugars are made from the same 
stock as the granulated sugar, but it is ground and bolted 
in a mill similar to that used for making flour. 

Cut sugar is made from the sugar loaves by sawing them 
in slices, and then cutting the slices into rectangular blocks 
by the use of a gang of small circular saws. 



SUGARS 197 

On account of the cheapness of sugar, there is little danger 
of adulteration, but lower grades are more readily adulter- 
ated than the best grade of granulated sugar. 

PROPERTIES OF CANE SUGAR 

Cold water dissolves three times its weight of cane sugar. 

Eapid boiling changes cane sugar to barley sugar, a trans- 
parent, noncrystalline mass, which has, however, the same 
chemical composition as sugar. 

Experiment 98. Melt a sample of cane sugar in an iron pan 
or spoon, and examine the product, which is known as 
" barley sugar/' 

If the sample is heated to 400° F., a substance called " cara- 
mel " results. This material is extensively used in confec- 
tionery, and is a harmless coloring matter for beer and 
other alcoholic liquors. 

Experiment 99. Heat a sample of sugar to a higher tem- 
perature than in Experiment 98, and dissolve the brownish 
substance so obtained in water. Notice the taste of the 
solution. "When cane sugar is heated with an acid or with 
many salts and metals, the change known as " hydrolysis " 
takes place. This action is catalytic, as the " hydrolyte " does 
not enter into chemical combination with the products formed. 
This hydrolysis of cane sugar to an invert sugar can be 
expressed by the equation: Ci 2 H 22 11 +H 2 = 2 C 6 H 12 6 . 

Experiment 100. To 50 cc. of a fairly strong solution of 
cane sugar add 5 cc. of hydrochloric acid, and heat the so- 
lution gradually to 70° C, and keep it at this temperature 
for a few minutes. By this treatment the sugar is "in- 
verted," and the presence of invert sugar may be determined 
by the Fehling's test, as noted in Experiment 82. 

The following table l gives the average composition of some 
common grades of sugar : — 

1 Thorp, " Outlines of Industrial Chemistry," p. 400. 



198 



SANITARY AND APPLIED CHEMISTRY 



Raw Sugars 



Good centrifugal 
Poor centrifugal 
Good muscovado 
Molasses sugar 
Manila sugar 
Beet sugar, 1st 

Refined Sugars 
Granulated or loaf sugar 
White coffee sugar . . 
Yellow sugar . . 

Barrel sirup . . 



Cane 
Sugar 


Glucose 


Water 


Organic 
Matter 


96.0 


1.25 


1.00 


1.25 


92.0 


2.50 


3.00 


1.75 


91.0 


2.25 


5.00 


1.10 


88.0 


2.80 


3.00 


3.50 


87.0 


5.60 


4.00 


2.25 


95.0 





2.00 


1.75 


99.8 


.20 







91.0 


2.40 


5.50 


.80 


82.0 


7.50 


6.00 


2.50 


40.0 


25.00 


20.00 


10.00 



Ash 

.50 

.75 

.65 

2.70 

1.25 

1.25 



.30 
2.00 
6.00 



THE FOOD VALUE OF SUGAR 

The food value of sugar has been summarized as 
follows : 1 — 

1. When the organism is adapted to the digestion of 
starch and there is sufficient time for its utilization, sugar 
has no advantage over starch as a food in muscular work 
except as a preventive of fatigue. 

2. In small quantities and in not too concentrated form, 
sugar will take the place, practically speaking, weight for 
weight, of starch as a food for muscular work, barring the 
difference in energy and in time required to digest them, 
sugar having here the advantage. 

3. It furnishes the needed carbohydrate material to or- 
ganisms that have as yet little or no power to digest starch. 
Thus milk sugar is part of the natural food of the infant. 

4. In times of great exertion or exhausting labor, the 
rapidity with which it is assimilated gives it certain 
advantages over starch. 



1 Mary Hinman Abel, Farmer's Bui. 93, U. S. Dept. Agric. 



SUGARS 199 



MALTOSE 



Maltose (C 12 H 22 O n + H 2 0) : this, together with dextrin, 
is made by the limited action of dilute acids or by the action 
of malt infusion on starch. This sugar probably does not 
ferment directly, but by the action of yeast its fermentation 
and conversion into dextrose go on simultaneously. It is an 
ingredient of commercial glucose, and is also the sugar 
produced by the action of the ptyalin of the saliva on 
starch, in the process of digestion. 

The equation for changing gelatinized starch to maltose is 
as follows : — 

CisH^Ois + H 2 = C 6 H 10 O 5 + C 12 H 2 20 n . 

Starch Dextrin Maltose 

When either dextrin or maltose is heated with dilute acid 
it is converted into dextrose. The hydrolysis in the case of 
maltose would be represented by the equation : — 

C^H^On + H 2 = 2 C 6 H 12 6 . 

Maltose Dextrose 



LACTOSE (MILK SUGAR) 

Lactose (C^H^On+HaO) is made commercially by treat- 
ing whey, a by-product in cheese making, with chalk 
and aluminum hydroxid, and after filtering off the precipi- 
tate thus produced, the filtrate is concentrated in a vacuum 
pan, and when sticks or strings are suspended in the sirup, 
after some time the milk sugar crystallizes on them. 

This sugar is not as sweet as cane sugar, but it is very useful 
in " modified milk " in making dietetic preparations, and as 
a basis for the pellets used by homeopaths. In the ordi- 
nary souring of milk this sugar changes to lactic acid. On 
being heated with dilute acids lactose is inverted, forming 
dextrose and galactose (see reaction under sucrose). 



CHAPTER XV 

THE GLUCOSE OK, GRAPE SUGAR GROUP, C 6 H 12 6 

It will be noticed that under the general name " glucose " 
there are grouped a number of substances made by " hydroly- 
sis " from starch, such as dextrose, and also substances 
such as levulose, which result from the inversion of cane 
sugar. 

COMMERCIAL GLUCOSE 

When the glucose is to be made from corn, the latter is 
steeped for some time in warm water, and the softened grain 
is crushed in a " cracker " to loosen the germs. The coarse 
meal passes to the " separators," where the germs being 
light float over the dam at the end of the tank. These germs 
are often used for making corn oil. The hulls and starchy 
matter are ground fine, and passed over " shakers " to re- 
move the hulls. The starch suspended in water is now 
ready for the next process. 

As previously stated, when starch is boiled with dilute 
acids it is converted into a mixture of compounds of the 
grape sugar group. The commercial process of manufacture 
is to treat the starch from perhaps 1000 bu. of corn suspended 
in water in a wooden vat of 3000 to 4000 gal. capacity with 
sulfuric acid, in the proportion of from \ to 1^ lb. of 
sulfuric acid (oil of vitriol) to 100 lb. of starch. The 
liquid is boiled by means of a steam coil with free or con- 
fined steam for several hours or till a sample tested with 
iodine gives no blue color. Closed " converters " are also 
used in this process and in this case the liquid is boiled 
under pressure. 

When the process of conversion has been carried far 

200 



THE GLUCOSE OR GRAPE SUGAR GROUP 201 

enough, the liquor is neutralized with marble dust, and the 
calcium sulfate thus formed is allowed to settle. The 
solution is filtered through bag filters or a filter press, and 
is then run through bone-black filters. Concentration in 
the vacuum pan is then effected. Some manufacturers filter 
several times through bone black, and some use sulfur dioxid 
gas to bleach the product and arrest fermentation. 

The process of hydrolysis would in part be represented by 
the equation — 

(C 6 H 10 O 5 )„ + K H 2 = .(C^Oe). 

A number of intermediate products are formed. 

When glucose is the product desired the conversion of the 
starch is arrested while there is still considerable of the 
uncrystallizable dextrin in the product. This gives a heavy 
sirup. If the conversion is more complete, and the concen- 
tration is carried farther, the product is a solid known as 
"grape sugar " 

In addition to the method mentioned for making glucose, 
another process has recently come into use and has in fact 
practically superseded the former process. The starch is 
converted to glucose by adding to it a small quantity of 
hydrochloric acid, and heating for some time under con- 
siderable pressure. The excess of acid is afterwards neutral- 
ized by sodium carbonate, and the small quantity of com- 
mon salt left in the product is said to improve it rather than 
otherwise. Some sodium sulfite is used to prevent, as far 
as possible, the caramelization. 

The composition of the two products made is as fol- 
lows : 1 — 

Glucose (liquid) Grape Sugar (solid) 

Dextrose 34.3% to 36.5% 72.0% to 99.4% 

Maltose . 4.6% to 19.3% 0%to 1.8% 

Dextrin 29.8% to 45.3% 0%to 9.1% 

Water 14.2% to 17.2% .6% to 17.5% 

Ash 32% to .52% .3% to .75% 

1 Leach, "Food Inspection and Analysis," p. 471. 



202 SANITARY AND APPLIED CHEMISTRY 

Glucose mixed with molasses is frequently used in the 
manufacture of table sirups ; in beer to take the place of 
malt ; in the manufacture of confectionery, of artificial honey, 
and of maple sirup, jellies, jams, vinegar, wine, etc. From 
some experiments made by the author, glucose is shown to 
be three fifths as sweet as cane sugar. 1 

As to the healthfulness of glucose, the committee of the 
National Academy of Science, to whom this question was 
referred some years ago, and from whose report many of 
the facts are gathered, say that there is no evidence of ill 
effects from its use. 

The report concludes thus: " First, the manufacture of 
sugar from starch is a long-established industry ; scientific- 
ally valuable and commercially important. 

" Second, the processes that are employed at the present 
time are unobjectionable in their character and leave the 
product uncontaminated. 

" Third, the starch sugar thus made and sent into com- 
merce is of exceptional purity and uniformity of compo- 
sition, and contains no injurious substances. 

"Fourth, having at best only two thirds the sweeten- 
ing power of cane sugar, yet starch sugar is in no way infe- 
rior to cane sugar in healthfulness, there being no evidence 
before the committee that maize or starch sugar, either in 
normal condition or fermented, has any deleterious effect 
upon the system even when taken in large quantities." 

The glucoses, maltose and milk sugar, reduce Fehling's 
solution, but starch paste must be converted by acid, and 
cane sugar must be inverted before testing. 

Experiment 101. Use a thin starch paste prepared from 
some of the starch made in Experiment 72. To 200 cc. of 
this, add about 20 cc. of dilute hydrochloric acid, and boil for 

1 Quarterly Rep. Kas. State Bd. Agric. 1885, p. 28. 



THE GLUCOSE OR GRAPE SUGAR GROUP 203 

15 m. Neutralize the solution with NaOH ; cool and test a 
portion, 1st, with iodin for starch; 2d, with Fehling's solu- 
tion for dextrose. There may be some dextrin present, in 
which case a purple color will be obtained by iodin. 

Experiment 102. Test a sample of commercial "grape 
sugar " for starch with iodin, and for a reducing sugar by 
Fehling's solution. 

Experiment 103. Macerate some raisins with water, filter 
the solution, and test a portion for grape sugar or invert 
sugar by Fehling's solution. 

Experiment 104. Crush an apple and squeeze the juice 
through a cloth, filter this, and test for the invert sugar. 
The sugar of fruit is usually invert sugar, and this like dex- 
trose has a reducing action with Fehling's solution. 

Experiment 105. Test a dilute solution of pure honey for 
a reducing sugar by Fehling's solution. 

Experiment 106. As sulfuric or sulfurous acid is often 
used in the manufacture of commercial glucose, it is some- 
times possible to detect adulteration of honey by the follow- 
ing test : Add to a dilute solution of commercial glucose a 
drop of hydrochloric acid and 2 or 3 drops of a solution 
of barium chlorid, and boil the solution. The formation of 
a white precipitate of BaS0 4 shows the presence of sulfuric 
acid or a sulfate. 

Experiment 106 a. As hydrochloric acid is now so gen- 
erally employed in making glucose, test a dilute solution of 
glucose for a chlorid by making slightly acid with nitric 
acid and adding a few drops of silver nitrate (see experi- 
ment 43). 

Experiment 107. Eepeat the above experiment, using a 
dilute solution of honey. 



204 SANITARY AND APPLIED CHEMISTRY 

Invert sugar is of importance, since it results from the in- 
version of cane sugar, and as it occurs in honey and many- 
fruits. It is a mixture of equivalent proportions of dex- 
trose and levulose. It does not crystallize readily, and is 
produced in the boiling of acid fruit juices with cane sugar, 
as in the making of jellies, etc. Some authorities claim that 
invert sugar is sweeter than cane sugar. One author, 1 how- 
ever, reports as the result of his experiments that invert sugar 
is five sixths as sweet as cane sugar. If this is the case, we 
should expect that more sugar would be required to sweeten 
canned fruit if added before cooking than if added after- 
wards. Fruit sugar, or levulose, is found in most fruits, and 
does not crystallize. Invert sugar is found abundantly in 
grapes, forming the yellowish white granular masses in 
raisins. Levulose is of importance as a food for diabetic 
patients, as they utilize it more easily than any other form 
of carbohydrates. 

Experiment 108. Test some dilute cranberry or currant 
juice with Fehling's solution for fruit sugar, then boil an 
equal quantity of the juice for 15 m. with a moderate 
amount of cane sugar, and test as above. Notice by the 
relative quantities of the precipitates whether the fruit acid 
has " inverted " some of the cane sugar. 

HONEY 

During the secretion of honey in the body of the bee, su- 
crose, which is the principal constituent of the nectar, is 
mostly changed to a mixture of dextrose and levulose. Wax, 
formic acid, and flavoring substances from the flowers are 
also present. It has been estimated that to obtain a kilo- 
gram of honey the bee must visit from 200,000 to 500,000 
flowers. In some tropical countries certain varieties of 
flowers furnish a honey that is poisonous. Genuine honey 
1 Willard, Trans. Kan. Acad. Science, Vol. X, p. 25. 



THE GLUCOSE OR GRAPE SUGAR GROUP 205 

should contain not more than 8 % of sucrose, not less than 
25 °J of water, not less than 0.25 <f of ash, and from 60 to 
75% of reducing sugar. Whenever the dextrose is in excess 
of the levulose, it indicates adulteration with glucose. If 
ash is high, the sample is regarded with suspicion. Honey- 
comb consists of waxy substances which are probably inca- 
pable of digestion but not necessarily injurious. 

The following analysis shows the average composition of 
genuine honey : * — 

Sucrose (by Clerget) 5% to 7.64% 

Invert sugar 66.37 % to 78.80 % 

Water 12.00 % to 33.00 % 

Ash 03% to .50% 

On account of the cost of honey the temptation to adul- 
teration is very great. Cane sugar and glucose are the com- 
mon adulterants. The expedient has also been tried of 
feeding bees upon glucose, but it is said that they do not 
thrive with this treatment. It is a common practice to put 
up the so-called "strained honey" in jars, with a piece of 
the comb or a dead bee, as evidence of its genuineness. 
Artificial combs are also made, but have not found much 
favor with bee keepers. Although genuine strained honey 
may be found upon the market, we usually regard all honey 
sold in this way with suspicion. As honey is actually richer 
in sugar than the malt extracts recommended for invalids, 
and as this sugar is nearly all in a form to be readily assimi- 
lated, it is considered valuable as a supplement to the other 
carbohydrates in the diet. 

Experiment 109. If honey contains dextrin, this is a good 
indication of adulteration with glucose. To test for dextrin 
add to the suspected sample 3 or 4 volumes of strong alcohol. 

1 Canadian Dept. In. Rev., Bui. 47. 



206 SANITARY AND APPLIED CHEMISTRY 

In the presence of dextrin, quite a precipitate will appear, 
but in genuine honey only a slight cloudiness. 1 

Experiment 110. If honey contains any notable quantity 
of calcium sulfate, this is a pretty good indication of its 
adulteration with glucose. Test some diluted honey with 
ammonium hydroxid and ammonium oxalate for calcium. 

1 Leach, loc. cit. p. 471, 



CHAPTER XVI 
ROOTS, LEAVES, STALKS, ETC., USED AS FOOD 

In addition to the starch-bearing vegetable products dis- 
cussed in Chapter XI, there are a number of roots which are 
not particularly valuable as sources of starch, but which 
give a variety to the food supply. 

The carrot belongs to the botanical order Umbelliferse, 
which includes many edible plants such as celery, parsnip, 
and parsley. Wild carrots have a very pungent odor and 
taste, but this has been modified by cultivation so as to be 
mild and agreeable. It is often necessary, however, to culti- 
vate a taste for all the vegetables of this class. Carrots con- 
tain no true starch, but about 2.5 % of pectose, gum, etc., 
4.5 % of sugar, 0.5 % of albuminoids, and 89 °/ of water. 
When carrots are boiled they lose over 90 % of their nutrient 
material. This fact suggests that to retain any food value 
at all, carrots should be cooked in a soup or stew. 

Parsnips have also been cultivated from the wild parsnip, 
which is, like the carrot, an umbelliferous plant. The pars- 
nip is somewhat more valuable as food than the carrot, as 
the former contains about 3.5 °J of starch, 5 % of sugar, 
3.7 °fo of gum, pectose, etc., 1.5 % of fat, 1.2% of albumi- 
noids, and only 82 % of water. It loses a large amount of 
nutrient material in boiling. 

Turnips belong to the order of Cruciferae. They contain 
pectose, 3 %, instead of starch, and are very low in albumi- 
noids and extractives. Turnips contain 92.8 °Jo of water ; 
in fact they contain more water than milk. They are of 

207 



208 SANITARY AND APPLIED CHEMISTRY 

little value, then, except for their flavor and to furnish variety 
to the bill of fare. 

Beets are a more important food than any of those just 
mentioned, for the ordinary garden beet has been cultivated 
so that it contains from 10 to 15 % of cane sugar, or about 
as much as the variety used for making sugar. Beets also 
contain 2.4 % of pectose, and more cellulose than the other 
roots. The addition of vinegar to boiled beets helps to 
soften the cellulose, and, it is said, does not interfere with 
the digestion of other carbohydrates. After beets are boiled 
they contain only 3 % of sugar. 

The leaves and stalks of many plants are valuable both 
for food and for relishes. One reason for this is on account 
of the large amount of mineral salts that they contain. 
Some of these would be tough and woody if grown under 
the ordinary conditions, but if they are grown very rapidly, 
in an exceedingly rich soil, or if they are grown partly 
underground, or in the shade, they are quite tender. 
Though this class of foods often contains over 90% of 
water, yet their value should not be overlooked, for the gluten 
and starch which they contain are often in such a condition 
that they can be readily assimilated. 

Prominent among foods of this class should be men- 
tioned the cabbage, cauliflower, and kale. The cabbage 
contains 5.8% of carbohydrate, 1.8% of nitrogenous matter, 
and 1.3% of mineral matter, but when cooked the per cent 
of water is increased to 97.4% and the other constituents 
decrease in like proportion. In general it may be said that 
the effect of cooking is to greatly diminish the amount of 
nutrients in this class of foods. The value of cabbage as a 
protection against scurvy, for those who are for a long time 
obliged to live on salted or canned meats, should not be over- 
looked. 

Cabbage is sometimes packed in salt and preserved under 



ROOTS, LEAVES, STALKS, ETC., USED AS FOOD 209 

the name of " sauerkraut." Here a fermentation takes place 
and various organic acids are formed. 

When cooked with potatoes to furnish the starch, and 
pork to furnish fat and a small amount of proteids, the 
deficiencies of cabbage are to some extent made up ; really, 
however, the cabbage is but a flavoring for other food and 
adds to its bulk. 

Many other succulent vegetables are used under the 
common name of "greens," and each has its agreeable 
flavor, and may be considered of value rather as a stimulant 
to the appetite than as a source of nutrient material. 
Among them may be mentioned : spinach, dandelion, endive, 
watercress, beet tops, narrow-leaved dock, and young poke 
sprouts. Lettuce, which also belongs to this class, contains 
a milky juice, having mild soporific properties, and consid- 
erable mineral salts especially potassium nitrate. Asparagus, 
which is in much more common use than most of the foods 
mentioned, in the wild state is a seashore plant. It con- 
tains a peculiar crystallizable principle called " asparagin," 
C 4 H 8 N 2 3 , which has diuretic properties. When served 
with toast, the combination is an agreeable and useful food. 
Celery when in its wild state was known as " smallage." 
By intense cultivation much of the disagreeable odor has 
been removed, and it has found great favor. On the con- 
tinent of Europe the root is boiled, but in the United States 
the stalks, which are grown so that they are protected from 
too much light, are eaten raw for their agreeable flavor. 

Rhubarb {Rheum raphonticum), under the name of 
"pie plant," is a useful garden production. The leaf 
stalks when cooked with sugar are used, on account of their 
flavor and the acid which they contain. As the plant is a 
slight laxative it may be useful in cases of constipation. 
Rhubarb contains a peculiar flavoring substance and con- 
siderable acid potassium oxalate. 



210 SANITARY AND APPLIED CHEMISTRY 

Experiment 111. Express the juice from several stalks 
of rhubarb and filter it. Add to some of the clear juice 
a little of a solution of calcium chlorid, and notice the 
precipitate of calcium oxalate produced. 

The onion, leek, and garlic are chiefly prized for their 
pungent volatile oil, rich in sulphur, which makes them 
useful in flavoring other food. 

The tomato, although not properly belonging to this 
class, may be here discussed. It is a native of South 
America, and was introduced into Europe in 1596. It 
has been grown and used in enormous quantities in the 
United States since about 1850. The raw tomato con- 
tains 91.9 % of water, 1.3% of nitrogenous matter, 5 % 
of carbohydrates and .7% of mineral matter, and there- 
fore is not very valuable as a nutrient, but is properly 
classed as a relish. 

Tomatoes probably owe their acidity to the presence of 
malic acid. When made into "catsup," the product 
is often grossly adulterated and colored with aniline col- 
ors, and various preservatives are also used. 

ALGiE, LICHENS, AND FUNGI USED AS FOOD 

The most important of the algae is the Irish or Car- 
rageen moss. When dried, as usually prepared for market, 
it contains 9.4% of nitrogenous matter and 55.4% of a 
vegetable mucilage. Its value as a nutrient is not fully 
understood. 

Iceland moss is darker in color than Irish moss and con- 
tains 8.7% of proteids and 70% of a lichen starch, which is 
unaffected by digestion, and probably does not form glyco- 
gen. It has not been proved that it has any value as food. 

The edible fungi are popularly classed as mushrooms and 
the poisonous ones as toadstools, but this is not a scientific 
classification. Mushrooms are employed not only for flavor- 



BOOTS, LEAVES, STALKS, ETC., USED AS FOOD 211 

ing, but also as food. They are grown in large quantities in 
Europe in caves and cellars, in an exceedingly rich soil. They 
contain from 1.19 to 6.1 % of proteids, and from 1.2 to 6 % of 
carbohydrates, but starch is not present among the carbohy- 
drates. Although the analysis shows considerable nitrogen, 
much of this is in such a combination that it is not available 
for nutrition. It is said that mushrooms are not easily di- 
gested, on account of the large amount of cellulose which 
they contain. Some authorities claim that their use as a 
nutritious food should be encouraged, while others believe 
them to be simply a rather expensive flavoring material. 
The varieties known as truffles and morels are quite popular 
in England and on the Continent. 

Unfortunately several varieties of mushrooms are ex- 
tremely poisonous. In some cases the symptoms of the 
poisoning do not appear till after more than twenty-four 
hours. The poisonous substance is an alkaloid, a glucoside, 
or a toxalbumin, and is of different composition in the dif- 
ferent varieties. 1 As the taste for mushrooms is being cul- 
tivated, a larger number of persons are becoming acquainted 
with the characteristics of edible mushrooms, and in some 
countries special pains is taken to educate the common 
people to recognize the nonpoisonous varieties. There seems 
to be no safe rule, however, by which we can distinguish 
between the poisonous and edible varieties, and it is hazard- 
ous for persons not well acquainted with fungi to attempt to 
do this. 
1 SeeU. S. Dept. Agric, Div. Microscopy, Food Products, 1893-1894. 



CHAPTER XVII 
THE COMPOSITION AND FOOD VALUE OF FRUITS 

The term "fruit," in the restricted sense, includes the pulpy- 
substance inclosing the seeds of various plants, and especially 
those which are edible in the raw state. 

Fruits are essential to the distribution of plants, and 
have been utilized by man as food, as an agreeable luxury, 
and an aid to digestion. In general it may be stated that 
the seed is surrounded by some sweet, or edible envelope, 
to attract birds, insects, and quadrupeds, and in this way 
insure the scattering of the seed over a wider extent of 
territory. 

The seed proper is surrounded by a fleshy portion known 
as the pericarp. A green fruit does not differ very much 
from the leaf in composition, but in the process of ripen- 
ing, under the influence of sunlight, the fruit undergoes 
a remarkable change in color, texture, composition, and 
flavor. During the change it ceases to act on air like a 
leaf, but begins to absorb oxygen, and give out carbon dioxid 
gas. 

As the process of ripening goes on, both the invert sugar 
and the sucrose increase and the starch and free acid de- 
crease. After the disappearance of the starch the sucrose 
disappears quite rapidly on account of its change to invert 
sugar. Malic acid appears to decrease, but this phenomenon 
is largely due to the fact that it is formed in the early life 
history of the fruit, and is diluted by its growth. These 
changes are very well illustrated by the examination of the 

212 



COMPOSITION AND FOOD VALUE OF FRUITS 213 



analyses of Ben Davis apples, which were made at different 
stages of their growth. 1 



Date of Analyses 



June 16 
June 30 
July 13 
July 28 
Aug. 18 
Sept. 24 
Oct. 15 
Oct. 23 
Oct. 30 
Nov. 5 



Total 
Solids 



13.63 
13.37 
13.58 
15.71 
14.92 
15.05 
14.86 
14.82 
14.68 
15.73 



Acid as 
Malic 



1.64 
1.27 

.89 
.78 
.52 
.52 

.43 
.41 



Starch 



2.23 
3.03 
3.72 
3.67 
3.16 
2.40 
1.46 
.94 



Sucrose 



0.49 
.67 
1.21 
1.13 
1.46 
2.59 
3.13 
3.92 
3.87 
3.71 



Invert 
Sugar 



2.35 
3.04 
5.09 
4.52 
4.36 
4.83 
5.30 
5.53 
5.84 
5.83 



It is supposed, while ripening, that the insoluble peetose 
changes into pectin and secondary substances of a gelatinous 
nature. The tannin that made the fruit astringent also dis- 
appears. As the fruit becomes over-ripe, some of the sugar 
and acid is oxidized, or otherwise changed, and the fruit 
loses its agreeable flavor. On cold storage this latter change 
is deferred by the low temperature, but a very short exposure 
to air, at ordinary temperature, causes the fruit not only to 
appear over-ripe, but to decay quickly. During the process of 
decay, which is assisted by fermentation, carbon dioxid and 
alcohol are at first formed from the sugar, and later the 
alcohol is oxidized to acetic acid, and finally in the decayed 
fruit the seed is set free, ready to start a new plant. 

Fruits owe their agreeable taste to the right proportion 
of the constituents mentioned in the table on p. 209, and to 
the compound ethers and essential oils that may be present. 

1 Bigelow, Gore, and Howard, U. S. Dept. Agric, Bu. Chem., Bui. 
94, p. 46. 



214 



SANITARY AND APPLIED CHEMISTRY 



These flavoring substances are many of them present in such 
small quantity that they are not mentioned in the analysis. 

The composition of some of the most important fruits, as 
purchased, and including the refuse, is given by Atwater 
and Bryant, 1 as follows : — 

FRUITS 





CO 




3 

o 
« 


H 
< 
fr 


3g 

*A ft 

< £ 
o o 

EH - 


M 

s 

H 
P 

M 

Q 


W 

GO 

4 


Apples 


25.0 


63.3 


.3 


.3 


10.8 


_ 


.3 


Blackberries 













86.3 


1.3 


1.0 


10.9 


2.5 


.5 


Cherries . 













76.8 


.9 


.8 


15.9 





.6 


Cranberries 













88.9 


.4 


.6 


9.9 


1.5 


.2 


Currants . 













85.0 


1.5 





12.8 





.7 


Figs, fresh . 













79.1 


1.5 





18.8 





.6 


Grapes . . 










25.0 


58.0 


1.0 


1.2 


14.4 





.4 


Muskmelon 










50.0 


44.8 


.3 





4.6 





.3 


Oranges 










2T.0 


27.0 


.6 


.1 


8.5 





.4 


Pears . . 










10.0 


76.0 


.5 


.4 


12.7 





.4 


Plums . . 










50.0 


74.5 


.9 





19.1 





.5 


Kaspberries 













85.8 


1.0 





12.6 


2.9 


.6 


Strawberries 










22. 


85.9 


.9 


.6 


7.0 





.6 


Watermelon 










59.4 


37.5 


.2 


.1 


2.7 





.1 



Some fruits that seem to " melt in the mouth " really do 
contain considerable soluble matter. It is a well-known 
fact that sugar disguises acids, and that an agreeable taste 
in preserved fruits is often due to a judicious mixture of 
the acid and the sweet. The most important nutritive 
material in fruits is in the carbohydrate group : of course 
there are some special fruits like the olive and the avocadro 
which contain large quantities of fats. Although starch is 
found at certain stages of growth, sugar is the most abundant 

!U. S. Dept. Agric, Office of Exp. Sta., Bui. 28. 



COMPOSITION AND FOOD VALUE OF FRUITS 215 

of the carbohydrates. This is usually invert sugar, but apri- 
cots, pineapples, and apples contain also cane sugar. This 
fact has an important bearing on the dietetic use of fruits, 
as invert sugar is, in some diseases, as diabetes, more easily 
assimilated than cane sugar. 

The pectous bodies referred to above are not very well 
understood, but are supposed to be related to the carbohy- 
drates. The insoluble galacto-araban is supposed to give 
the property of hardness to unripe fruits and vegetables, and 
is the basis for the making of jelly. The statement has been 
made that as the fruit becomes riper the pectose is changed 
by the action of acids into pectin, a vegetable jelly, which 
causes the juice after boiling to gelatinize when cooled. This 
may be noticed in the juice that exudes in the baking of apples. 
It is supposed that by too long boiling these pectous com- 
pounds are concentrated into a more soluble modification, and, 
if this is true, it may explain the fact that sometimes fruit 
juices that have been boiled for a long time become thick 
and viscid, but do not form a true jelly. A partially ripe 
fruit is better adapted to making a jelly than one that is 
fully ripe. 

From what has been said it is evident that pectin bodies 
are substances of undetermined function very widely dis- 
tributed in plant tissues. They occur both in soluble and 
insoluble forms. 

In the study of these bodies "the most important problem 
appears to be the quantitative determination of the pectin 
bodies occurring in a given tissue, because such a method 
could be used to determine the function of the material in 
plants : whether, for example, it is a reserve material, a by- 
product, is used for structural purposes, or has all three 
functions or two of them ; whether the nature of the pectin 
body changes with the growth of the tissue, or possesses a 
practically constant composition ; whether the pectin bodies 



216 SANITARY AND APPLIED CHEMISTRY 

obtained from different sources are identical, are mixtures 
of the same substances (such as araban and galactan) in 
varying proportions, or are inherently different. " 1 

Experiment 112. To the filtered juice of a ripe apple add 
an equal bulk of alcohol, and a gelatinous mass consisting 
largely of pectin will be precipitated. This may be dried, 
and it will be found that the powder thus obtained is solu- 
ble in cold water. 

Experiment 113. Stew a handful of cranberries, filter the 
juice, and allow it to stand till cold, when an abundant jelly 
is obtained. 

Experiment 114. Test some green fruit, a persimmon 
or banana, for tannin by extracting the juice, filtering, and 
adding a small quantity of ferric chlorid. The production 
of a black, or greenish-black, color indicates tannin. 

The acidity of fruits is due to the presence of the free 
acids, malic, citric, tartaric, or racemic, or their acid salts. 
They not only have an agreeable acid taste, and they serve 
as appetizers, but when oxidized in the body are converted 
into the corresponding carbonates, and these help to render 
the blood more alkaline and the urine less acid. 

Malic acid (H 2 C 4 H 4 05) is found in many acid fruits, as 
cherries, apples, raspberries, gooseberries, rhubarb, unripe 
mountain ash berries, etc. 

Experiment 115. Add to a solution of malic acid, calcium 
chlorid, ammonium chlorid, and ammonium hydroxid in 
excess. There should be no precipitate, but upon adding 
to this 3 volumes of alcohol, calcium malate (CaC 4 H 4 6 , 
3H 2 0) should separate out as a precipitate. 

iBigelow, Gore, and Howard, U.S. Dept. Agric, Bu. Chem., Bui. 

94, p. 86. 



COMPOSITION AND FOOD VALUE OF FRUITS 217 

Experiment 116. Since the acid potassium malate exists 
in the stalks of the common rhubarb, the juice that is ex- 
pressed from this may be filtered and tested for malic acid 
by the test described in Experiment 115. 

Citric acid, H 3 C 6 H 5 7 , occurs in the juice of lemons, cur- 
rants, unripe tomatoes, gooseberries, etc. It is made on a 
large scale from lime or lemon juice, by saturating the juice 
with chalk; the precipitate of calcium citrate is decom- 
posed by an equivalent quantity of sulfuric acid and filtered 
from the calcium sulfate. Evaporate the nitrate and crystal- 
lize out most of the calcium sulfate, and from the mother 
liquor allow the citric acid to crystallize. 

Experiment 117. Make citric acid from the juice of at 
least two lemons, as above described. 

Experiment 118. Add a moderate quantity of calcium 
chlorid to a concentrated solution of citric acid, and then 
add sodium hydroxid till the solution is nearly neutral. 
Calcium citrate, Ca 3 (C 6 H 5 7 ) 2 , will be formed. 

Experiment 119. Try the above test with a concentrated 
and filtered sample of lemon juice, and note the formation 
of the precipitate of calcium citrate. 

Tartaric acid (H 2 C 4 H 4 6 ) is found in many fruits, particu- 
larly ripe grapes, as acid potassium tartrate (KHC 4 H 4 6 ). 
When the "must" ferments the "cream of tartar" precipi- 
tates as the alcohol increases, and this precipitate is known 
in the market by the name of " argol," or crude tartar. It 
is frequently much contaminated with calcium sulfate, 
which is used in " plastering " the wine. To make tartaric 
acid from this, the solution of the argols is treated with 
milk of lime to form the calcium tartrate, and the latter salt 
is suspended in water and treated with an equivalent of sul- 
furic acid, and the calcium sulfate so formed is filtered off, 



218 SANITARY AND APPLIED CHEMISTRY 

and the tartaric acid is obtained in crystals by concentration 
of the filtrate. 

Experiment 120. Add to a concentrated solution of tar- 
taric acid a concentrated solution of potassium chlorid, when 
a precipitate of acid potassium tartrate will be formed on 
shaking and allowing to stand at ordinary temperature. 
The test is more delicate if the solution is nearly neutral- 
ized with sodium carbonate before the potassium chlorid is 
added. 

Experiment 121. Make a similar experiment with filtered 
grape juice, which may conveniently be obtained from 
canned grapes. A more delicate test is made by adding to 
100 cc. of the fruit juice a few drops of strong acetic acid, a 
few drops of a concentrated potassium acetate solution, and 
15 g. of pure, finely ground potassium chlorid; dissolve the 
latter salt by shaking and add 20% of 95% alcohol. Stir 
and shake vigorously to assist in the crystallization of the 
acid potassium tartrate. 

Cultivation has changed the character of many fruits, 
and has much improved their flavor, so that many luscious 
fruits have been developed from disagreeable, or, to say the 
least, very medium stock. Cooking improves many fruits 
by softening the cellulose and converting the gums and al- 
lied bodies into a gelatinous form. Sucrose is inverted 
and pectin bodies converted into soluble forms. If there is 
starch remaining, this is made more digestible by cooking. 
There are many fruits that in the raw state are not suitable 
to use as food for persons with dyspeptic tendencies. They 
are, however, very satisfactory and useful when suitably 
cooked. Apples, pears, quinces, and cranberries belong to 
this class. It should also be noted that a jelly made from 
a fruit juice is usually much more acceptable to an invalid 
and less irritating in its action than the raw fruit or the 



COMPOSITION AND FOOD VALUE OF FRUITS 219 

jam. This is especially true of raspberries, blackberries, and 
currants, on account of the numerous fine seeds that are 
present in the jam. 

JAMS AND JELLIES AND THEIR ADULTERATION 

Although a few years ago preserved fruit products were 
all prepared by the housewife, at the present time much of 
this work is turned over to the manufacturer, and he has 
the opportunity and often the incentive to falsify the mate- 
rial, and to give it a fictitious value in color, odor, sweetness, 
flavor, and preservative qualities. Much work has been done 
on this subject by the United States Department of Agri- 
culture and at State Experiment Stations. The presence in 
these products of anything in addition to the fruit and cane 
sugar should be regarded as an adulteration. If they are made 
up with foreign materials they should, in the interest of 
the purchaser, at least be labeled "compound." 

The substitute for jam and jelly, which is sold at say 
10 ff per half-pound jar, is often made of apple juice or refuse 
from canning factories, and glucose, or starch, colored with 
coal-tar dyes to imitate any natural product, as straw- 
berry, currant, etc., and occasionally flavored with an 
artificial fruit essence. Sometimes a little " saccharin " is 
added to give a sweeter taste than the glucose would im- 
part, and usually some preservative, as salicylic acid, sodium 
benzoate, or sulfite is used. 

As it is difficult to secure sufficient stiffness in an apple- 
jelly stock with glucose, a little alum and sulfuric acid or some 
tartaric or phosphoric acid is added to cause the mass to 
gelatinize. 1 In the cheapest jellies, since there is very little 
pectin or malic acid, starch, and agar-agar are sometimes 
added to cause the mass to thicken sufficiently. 

Foreign seeds, like that of the clover, are sometimes used. 
1 Leach, u Food Inspection and Analysis," p. 716. 



220 SAXITAKY AND APPLIED CHEMISTRY 

Although a sample of jam may contain the seeds of the 
genuine fruit, and so appear to be genuine, yet the fruit may 
be first used to make a high grade of jelly, and the residue 
may be afterwards worked up into a cheap jam. 

Experiment 122. The test for a coal tar dye in jelly 
may be made as follows : Strips of a fine woolen cloth, such 
as " nun's veiling," are boiled with a solution of soap, and 
then thoroughly washed. One of these strips is then boiled 
for about 15 m. in a diluted, filtered solution of the jam or 
jelly, to which a little potassium bisulfate has been added. 
The wool is then boiled with water containing a little soap, 
and if it has been colored at all with the dye it is digested 
with dilute ammonia, which will dissolve the colors fixed in 
the acid bath. The fabric is then removed from the bath. 
Slightly acidify the solution, and boil with a new piece of 
the fabric. This second dyeing will fix the coal tar colors, 
but will not fix the natural fruit colors. There are a few 
rather uncommon coloring matters, made by chemical 
methods of manufacture from vegetable substances like cud- 
bear and archil, which are not to be distinguished from ani- 
line dyes by any method of dyeing. 1 

Experiment 123. To detect starch in jelly, heat an 
aqueous solution of the sample nearly to the boiling point 
and decolorize by the addition of several cubic centimeters 
of dilute sulfuric acid and afterwards a small quantity of 
potassium permanganate. Cool the solution, filter if neces- 
sary, and test for starch by the iodine reagent as usual. Only 
a small quantity of starch, but enough to give a very charac- 
teristic test, is normally present in apple juice. 2 

For testing for preservatives, see Chapter XXY. 

1 Winton, J". Am. Chem. Soc, 22, 1900, p. 582. 
2 U. S. Dept. Agric, Bu. Chem., Bui. 65. 



COMPOSITION AND FOOD VALUE OF FRUITS 221 

FRUIT SIRUPS; FLAVORING EXTRACTS 

Many fruit sirups are upon the market, which are pre- 
pared to use with sugar as the basis of beverages either 
carbonated or otherwise. These sirups may be made from 
genuine fruit, sterilized by heating, and put up practically 
like canned fruit, or they may be entirely artificial, like 
some of the jellies just mentioned. 

Among the flavoring extracts, that of vanilla and lemon 
are most extensively used. Practically, only a small pro- 
portion of the vanilla extract on the market is made wholly 
from the vanilla bean, as this is very expensive. Most of 
the agreeable flavor of vanilla extract is due to the presence 
of a body called vanillin, C s H s 3 . Many of the cheaper 
so-called vanilla extracts on the market are made by the use 
of the Tonka bean, which contains the active principal 
coumarin, C 9 H d 2 . Some manufacturers claim that the 
quality of the extract is improved rather than otherwise by 
the use of the Tonka bean. 

Much of the ordinary " compound M vanilla extract is made 
by the use of the artificial vanillin, and the artificial cou- 
marin, with some coloring matter and sugar, added to a 
weak alcoholic tincture of the Tonka bean. 1 

Experiment 123 a. Place some extract of vanilla in an 
evaporating dish on a water bath and evaporate off half of 
the liquid. Add cold water to make up to the original 
volume. By this treatment the alcohol will be driven off, 
and in the watery solution that is left the substances in true 
vanilla are nearly insoluble, so the liquid will be cloudy and 
of a dirty brownish color. The artificial extract, on the 
other hand, will be bright and clear. 

Experiment 123 b. Add a little of a solution of sugar of 
lead to some of the extract of vanilla. The true vanilla 
!Lab. Inl. Rev. Dept. Can., Bate. 89 and 114. 



222 SANITARY AND APPLIED CHEMISTRY 

extract will give an abundant yellowish brown precipitate 
and a pale yellowish liquid. Upon the artificial extract the 
lead solution has but little effect, and there is only a slight 
discoloration. Another test is to notice the character and 
color of the foam produced on shaking some of the artificial 
vanilla extract. The bubbles will retain their bright caramel 
color till the last ones have disappeared, while, if the extract 
is genuine, the bubbles are much lighter in color. 

Extract of lemon should contain, according to the U. S. 
Pharmacopoeia, 5% of oil of lemon,and to keep this in solu- 
tion will require alcohol of 80 °J strength by volume. Much 
of the extract of lemon on the market contains only a trace 
of the oil, and less than 40 % of alcohol. A sample of alcohol 
so dilute as this will dissolve only a very small quantity of 
the oil, although there may be enough to give the extract a 
slight taste and odor. Such extracts are usually colored 
yellow by the use of coal tar dyes. 1 

Experiment 123 c. To 50 cc. of water add 10 cc. of the 

extract of lemon to be tested. If the solution becomes milky, 
on account of the precipitation of the oil of lemon, it is of 
good quality, but if it remains clear only traces of the oil are 
present. 

Most of the artificial fruit essences, such as that of straw- 
berry, banana, raspberry, apple, and pineapple, are made by 
ingeniously combining various compound ethers, organic 
acids, and essential oils. These are usually colored with 
aniline colors, and may be sweetened by the use of glucose 
or saccharin. 1 

1 \J. S. Dept. Agric, Bu. Cheni., Bui. 65. 



CHAPTER XVIII 
EDIBLE FATS AND OILS 

The fats used in the manufacture of soap have already- 
been discussed, but the importance of certain fats and oils 
in food products warrants some further attention to them in 
this connection. The facility with which a fat saponifies 
(see p. 98) is of great importance in the process of digestion. 
The fats are insoluble in water, but readily soluble in ether, 
chloroform, oil of turpentine, and similar solvents. 

Like starch and sugar, the fats do not directly form 
muscular tissue, but they have 2\ times the power to 
maintain the heat and activity of the body that the 
carbohydrates possess. There seems to be little difference 
whether the fat comes from a vegetable or an animal 
source. 

The amount of fat existing in some food products is 
as follows: — 



From vegetable sources : ■ 



Almonds 
Peanuts 
Olives (pulp) 
Cacao . . 
Flax seed . 
Cocoanut . 
Cotton seed 



Per Cent 




Per Cent 


54.0 


Sunflower seed . . 


. 20.5 


41.6 


Oatmeal .... 


. 6.0 


56.4 


Indian corn (white) . 


. 4.2 


44.0 


Wheat bran . . . 


. 4.0 


38.0 


Peas 


2.5 


68.7 


Wheat flour . . . 


. 1.0 


20.1 







223 



224 SANITARY AND APPLIED CHEMISTRY 

From animal sources : — 

Per Cent Per Cent 

Butter 84.4 Poultry 16.3 

Bacon 65.0 Mackerel 13.0 

Mutton chop .... 35.0 Eggs (whole) .... 11.0 

Cheese 30.0 Cow's milk 4.0 

When fat is deposited in the body beneath the skin it 
keeps in the warmth of the body. The fat wherever depos- 
ited may be reabsorbed into the blood, and thus keep up 
the animal heat for a long period even when food is not 
taken. This is the case with animals which hibernate for 
several months. 

The demand for some of the oils has been constantly 
increasing. Previous to 1870 it was quite a problem to the 
cotton planters how they should dispose of their cotton 
seed, while to-day the oil extracted from it finds numerous 
uses. A large quantity is exported to Europe, where it 
is used in the manufacture of soaps and butterine, and oc- 
casionally as an adulterant for olive oil. Cotton-seed oil is 
used in the United States in canning factories, in the pres- 
ervation of fish, in the manufacture of " cottolene," butter- 
ine, and soap, and for the preparation of salad dressing. 

The oil of the cocoanut is also exceedingly valuable, both 
for cooking and in the manufacture of soap. It is imported 
from various tropical countries, especially Ceylon and the 
East Indies. Unfortunately, the oil soon becomes rancid, 
and therefore it is more extensively used for food in the 
countries where it can be freshly obtained than elsewhere. 

LARD 

The " rendered " fat of the hog has the general name of 
lard, but there are several different grades made at the 
packing-house. The lowest grade, known as " steam-ren- 
dered " lard, or " prime steam lard," is extracted from the 



EDIBLE FATS AND OILS 225 

stock by admitting steam to the tank under a pressure of 
40 to 50 lb. The object of cooking lard or suet material 
is to break the membranous cells, thus allowing the fat to 
escape, and to heat the small quantity of the nitrogenous 
portion that may remain in the finished product so that it 
will not readily decompose. 

A " refined lard " is sometimes made from the " prime 
steam lard " by heating it in a tank to 170° F. and blowing 
in air for some time to remove moisture. It is then bleached 
at a temperature of 150° to 165° F., by agitation with Fuller's 
earth (clay of a peculiar composition), and filtered through 
a filter press. The final operation in the manufacture con- 
sists of cooling rapidly, either by agitating in a tank sur- 
rounded by cold water, or by running the lard on to a large 
roll, which is filled with ice-cold brine, and which slowly 
revolves. 

Kettle " rendered " lard is that which is made in kettles 
heated externally, and corresponds to ordinary household 
lard. The best grade of " leaf lard w belongs to this class. 
The material, which has been thoroughly washed, is heated 
at as low a temperature as possible to secure the result, in 
steam -jacketed kettles, and when fully rendered is drawn 
off into a settling tank, before being filled into packages for 
shipping. The " scrap " remains in the bottom of the ren- 
dering kettle, and is worked over again. 

The method of making " neutral lard/' which is made 
from leaf lard principally, is described under oleomargarine 
(Chapter XXI). As it is not fully heated, its keeping quali- 
ties are not good, and it must be kept in cold storage. 

Lards are sometimes " stiffened " so that they will not 
melt so readily in a warm climate, and if this is done by 
the addition of lard stearin it is not considered an adultera- 
tion, but the use of the oleostearin from beef should be 
considered an adulteration. 

Q 



226 



SANITARY AND APPLIED CHEMISTRY 



" COMPOUND LARD," " COTTOLENE," " COTTOSUET" 

There are a number of products on the market which do 
not pretend to be lard, but are made to use for the same 
purposes, and can be sold at a lower price. Different mix- 
tures of fats are used for the trade of different countries, 
and for summer and winter trade. The chief materials 
used are : cotton-seed oil, oleostearin, tallow, and sometimes 
lard. These materials are each carefully bleached before 
being mixed. 

THE COMPOSITION AND FOOD VALUE OF NUTS 

Within the last few years nut preparations have ap- 
peared on the market, so that their use as food should be no 
longer ignored. Nuts have a much higher nutritive value 
than fruits, as can be readily seen from their composition. 1 



Nuts as Purchased 


Refuse 


Water 


Pro- 
tein 


Fat 


Total 
Carbo- 
hydrate 


Ash 


Almonds .... 


45.0 


2.7 


11.5 


30.2 


9.5 


1.1 


Chestnuts . . . 


16.0 


37.8 


5.2 


4.5 


35.4 


1.1 


Cocoanuts . . . 


48.8 


7.2 


2.9 


25.9 


14.3 


.9 


Hickorynuts . . 


62.2 


1.4 


5.8 


25.5 


4.3 


.8 


Pecans .... 


53.2 


1.4 


5.2 


33.3 


6.2 


.7 


Peanuts .... 


24.5 


6.9 


19.5 


29.1 


18.5 


1.5 



Since they contain a large amount of fat, various nut 
preparations are used as substitutes for butter. On account 
of the fact that nuts are not readily digested in the stomach, 
the attempt has been made, and with considerable success, 
to improve the product, by crushing and removing the excess 
of oil and cellulose. 

Chestnuts, which are used very extensively as food by the 

1 U. S. Dept. Agric, Office Exp. Sta., Bui. 28. 



EDIBLE FATS AND OILS 227 

peasants of southern Europe, have been mentioned under 
the starchy foods. 

In the almond-producing countries the nut is eaten both 
green and dry. When the skin has been softened by soak- 
ing for some time in warm water, it may be removed and 
the nuts are said to be " blanched." 

It is interesting to note that there are two kinds of 
almonds, the sweet and the bitter, both of which contain 
a peculiar ferment called "emulsin." The bitter almond 
contains, in addition to this, an interesting " glucoside " 
known as amygdalin, C^H^NOu + 3 H 2 0. This, in the 
presence of water, is broken up by the emulsin into glucose, 
benzoic aldehyde, and hydrocyanic acid, HCN. It is on ac- 
count of the formation of this latter compound that bitter 
almonds are poisonous. Amygdalin is also obtained from 
the seeds of plums, peaches, cherries, apples, etc. 

The cocoanut is probably the most important of any 
nuts to a large number of people. As the edible part or 
meat contains about 50% of oil, the abundance of nutrient 
material can be readily appreciated. Each tree yields from 
80 to 100 nuts a year, and will continue to bear for at least 
two generations. The importance of the oil in various in- 
dustries, such as that of soap and candle making, should not 
be overlooked. 

The peanut, although not properly a nut, as it belongs to 
the leguminous family, since the edible portion contains 
about 38% of oil, may properly be considered here. As it 
contains about 25% of albuminoids, and considerable starch, 
it very deservedly is coming into more general use both as a 
food for man and for cattle. Three hundred million pounds 
of peanuts are grown annually for use in the United States. 
The principal peanut-producing states are Virginia and North 
Carolina. As sweet almonds and peanuts resemble meat in 
their high proteid and fat content, they may be used to a 
certain extent to take the place of meat. 



CHAPTER XIX 
NITROGENOUS FOODS 

In Chapter X it is stated that foods are divided into 
two general classes, carbohydrate and nitrogenous, and that 
the carbohydrate foods contain sugars, starches, dextrins, 
and fats, and also that there are many foods that contain 
both classes of nutritive materials. The relation between 
these different foods may be seen by comparing the composi- 
tion of the cereals and the leguminous foods. 

If, however, we wish to make use of a concentrated nitrog- 
enous food, it is possible to utilize the system of some animal 
that subsists on vegetable food, and so we use as nitroge- 
nous foods, beef, mutton, lean pork, fish, oysters, poultry, 
game, milk and its products, and eggs. Of all these, beef 
may be regarded as the most typical nitrogenous food, and 
it is, no doubt, the most valuable meat for all purposes. 

Animal foods leave comparatively little residue, as they 
are practically completely digested ; they form, then, a con- 
centrated food. Not only are the animal foods of agreeable 
flavor, but they contain mineral salts, which are of great 
value in the nutrition of the body. 

" Since, in some way as yet unknown to us, nitrogen is 
essential to living matter, such substances as contain this 
element in an available form are of first importance. Some, 
as albumen, are so closely allied to human protoplasm that 
they probably need only to be dissolved to be at once assimi- 
lated. Others, as gluten and similar vegetable products, 
undergo a still greater change ; while still others, as gelatin, 

228 



NITROGENOUS FOODS 229 

have a less profound but marked effect in protecting the 
tissues from waste. Still other nitrogenous substances, 
as the alkaloids, seem to affect the nerve tissue for good or 
ill. The enzymes, ' ferments ' in part, of the older nomen- 
clature, are also highly nitrogenous substances, present in 
some form in nearly all the foodstuffs of natural origin. The 
nearer the composition of the food approaches to the proto- 
plasmic proteid, presumably the greater its food value, since 
each cleavage, each hydrolysis, each step in the breaking 
down of the highly complex molecule, consisting of hundreds 
of atoms, is supposed to liberate stored energy. Therefore 
it is not a matter of indifference in what form this essential 
is taken." 1 

CLASSIFICATION OF NITROGENOUS FOODS 

The following is a convenient classification of nitroge- 
nous bodies that occur in food. 2 

I. Proteids. These bodies contain nitrogen, oxygen, hy- 
drogen, carbon, and sulfur, and are capable of being con- 
verted, in the body, into proteoses and peptones. They 
may be present in either animal or vegetable food. Under 
this general head the following divisions are made : — 

1. Albumins, which occur in eggs, milk, cereals, etc. 

2. Globulins, which occur in serum, in blood, as myosin 
in meat, as vitellin in egg yolk, and as vegetable vitellin in 
cereals and in peas, beans, etc. 

3. Albuminates, occurring in casein of milk, in peas and 
beans, and in almonds. 

4. Proteoses, which occur in sour milk, ripened cheese, 
and wheat flour. 

5. Peptones, 3 which are found in meat. 

1 Richards and Woodman, " Air, Water, and Food," p. 142. 

2 Leach, " Food Inspection and Analysis," pp. 36-41. (From Watts's 
Diet, of Chem. Vol. IV.) 3 Found only in small quantities. 



230 SANITARY AXD APPLIED CHEMISTRY 

6. Insoluble proteids, such as fibrin and myosin, in ani- 
mal foods and gluten in wheat. 

II. Albuminoids. These are much like the proteids, and 
may be divided into, — 

1. Collagen, which composes the fibers of connective 
tissues. 

2. Gelatin, which is made by boiling bones. 

3. Mucin, which is found in meat and also in mucus. 

4. ZSTuelein, which occurs in the nuclei of cells in the 
egg yolk and milk. 

5. Chondxin. a substance that may be obtained from car- 
tilage by long boiling. 

6. Elastin, which forms the elastic fibers of connective 
tissue. 

III. Amides, amido-acids, and allied products, in- 
clude cholin (C 3 H 15 ZST0 3 ), betain (C 5 H u X0 2 ), and asparagin 
(C 4 H S XA). 

IV. Alkaloidal substances, such as those occurring in 
the beverages, tea. coffee, cocoa, and kola. 

V. Nitrogen, as nitrates. 

VI. Nitrogen, as ammonia. 

VII. Lecithin (C^H^XPO.^. which is found in egg yolk, 
cereals, and legumes. 

"The function of the albuminous substances is probably 
threefold, as they contribute to the formation and repair of 
the tissues and fluids of the body, and in a special manner 
of the nitrogenous tissues : they regulate the absorption and 
utilization of oxygen, and so play an important part in the 
chemistry of nutrition ; and under special conditions they 
may also contribute to the formation of fat, and to the de- 
velopment of muscular and nervous energy, and to the pro- 
duction of heat."' 1 

1 1. B. Yeo, i; Food in Health and Disease." p. 13. 



NITROGENOUS FOODS 231 

The structure of lean meat may be compared to bun- 
dles of tubes or fibers filled with rich nitrogenous juices. 
These fibers are soft and tender in the young animal, but 
with age the muscles become toughened and more firmly 
bound together. This muscular tissue is divided into two 
classes : the voluntary, or striated muscles, like those of the 
shoulder; and the involuntary, or nonstriated muscles, like 
those of the heart. The latter are not considered so valuable 
for food. The substance of the connective tissue consists 
chiefly of the albuminoids, elastin, and collagen, the 
latter being a substance which is changed by boiling 
with water or treatment with acids into gelatin. The pro- 
teids of the meat juice consist chiefly of the globulin myosin, 
muscle albumen, and muscle pigment. 

In the living muscle, while there are no peptones, the fer- 
ment pepsin is present, and after death, by the action of the 
pepsin in the presence of lactic acid, a portion of the normal 
proteid of the muscle seems to undergo a kind of digestion, 
so that in the meat traces of both peptones and proteoses 
are found. Ordinarily these latter bodies are the result of 
some digestive action on higher proteids. We have also 
present in the meat, creatin, xanthin, etc., which are known 
as flesh bases. It is evident that the nitrogenous bodies 
constitute the bulk of lean meat, while the carbohydrates 
are almost entirely lacking. It should be noted that the 
different " cuts " of meat have entirely different food values. 
It is not possible by a chemical analysis to distinguish be- 
tween the meat from different animals. 

Since myosin has the property of clotting after death, 
the meat undergoes the process of muscle stiffening or 
rigor mortis. If the meat is allowed to stand till this con- 
dition has passed off, on account of the resolution of a part 
of the myosin, and the partial digestion from the pepsin pres- 
ent, it becomes tender again. This process should not be 



232 



SANITARY AND APPLIED CHEMISTRY 



allowed to go too far, or the meat will become " high," and 
have a disagreeable odor and flavor. 

The character of the extractives very much modifies the 
flavor of the meat, and if these extractives are removed 
by prolonged boiling or digestion with water, the meat has 
very little taste. The following analyses show the propor- 
tion of the important ingredients in one kind of meat: — 

EFFECT OF COOKING 

Lean Beef 1 

Proteid . . . .18.36 
Gelatin (Collagen?) 1.64 

Fat 90 

Extractives . . . 1.90 

Ash 1.30 

Water . . . .75.90 



Rjlw Beep 2 


Roasted Beef 2 


Water . . 70.88 


55.39 


Nitrogenous 




matter 22.51 


34.23 


Fat . . . 4.52 


8.21 


Extractives 0.86 


0.72 


Min'l Salts 1.23 


1.45 



THE USE OF ANIMAL FOOD 

According to Mulhall the quantity of animal food used 
per year per capita is as follows in the different countries : 

Pounds Pounds 

United States 120 Scandinavia 67 

Great Britain 105 Austria 64 

France 74 Spain 49 

Germany ......... 69 Russia 48 

Belgium and Holland .... 69 Italy 43 



COOKING OF MEAT 

The general object of cooking food has already been dis- 
cussed (p. 120). In the case of meat, a high temperature not 
only softens the fibers and makes the product more agree- 
able to the taste, but it is only in this way that we can be 
sure that pathogenic bacteria and parasites are destroyed. 

The following processes of cooking may be applied to 
meat : boiling, roasting, broiling, baking, stewing, frying, 
i Bischoff & Voit. 2 Konig. 



NITROGENOUS FOODS 233 

In the cooking of meat it is essential to know the object 
desired in the process. If we want an extract, the meat 
should be placed in cold water and kept at a temperature 
below 160° F., for several hours, with the addition perhaps 
of a little salt. This is the method for extracting the nutri- 
tive material for making soup. Eecent experiments, how- 
ever, show that there is not as much difference in the com- 
position of meats immersed in cold water and then cooked 
at 85° C, and those plunged at once in boiling water and 
cooked at 85° C, as was formerly supposed. If, on the other 
hand, we desire to retain the rich juices in the meat, it must 
be heated as quickly as possible, especially on the outside, so 
as to prevent the escape of these juices with their accompany- 
ing flavors. 1 This is done most practically by broiling the 
meat, and to some extent by baking or roasting. The process 
of frying meat is very unsatisfactory and affords a product 
that is tough and unwholesome. 

The greater part of the proteids, both animal and vege- 
table, are coagulated at about 170° F. Fats are not as much 
affected by heat as carbohydrates and proteids, but when they 
are heated to a high temperature, they are liable to become 
partially decomposed. It is reasonable then to suggest that 
if meat is boiled, in order to retain the juices which it con- 
tains, the meat should be plunged into boiling water for a 
few minutes, thereby sealing up the juices within the fibers, 
then lowering the temperature for the thorough cooking 
of the meat. If a small quantity of water is used, less of 
the soluble material will be extracted. The average loss 
in weight when meat is cooked in hot water is about 34 %. 2 

In the process of roasting, especially when the meat is 
" basted," the same method for sealing up the tubes is used, 
so that the juices may be retained. This is still better accom- 

1 Grindley, U. S. Dept. Agric. Office Exp. Sta., Bui. 162. 

2 Loc. cit. 



234 SANITARY AND APPLIED CHEMISTRY 

plished in broiling or grilling, because the heat that is at first 
applied is more intense and later the meat has an opportu- 
nity to cook toward the interior, so that the flavor is supe- 
rior and the agreeable extractives are largely retained. 

In stewing or preparing a " pot roast, " as the heat is low 
and long continued, and as the juices that happen to be 
extracted are all served with the meat, the process is very 
satisfactory. If the temperature in stewing is not allowed 
to rise above 180° F., the meat will fall apart readily, and 
the proteids will not be coagulated, hardened, or rendered 
indigestible. It is an interesting fact that while vegetable 
foods take up water when they are boiled, animal foods 
actually lose water. According to some recent investi- 
gations 1 the average amount of water in 14 samples of un- 
cooked meats was 70.08 %, while in the 31 samples cooked 
in hot water it was only 57.50 %. 

BEEF EXTRACTS 

There has been much discussion as to the nutritive value 
of beef extracts, and the conclusion seems to be that the 
commercial extracts are not as valuable as a simple beef 
extract made by slightly broiling the beef and then squeez- 
ing out the juice. It is a mistake to suppose that 1 lb. of 
beef extract contains the soluble constituents of 20 to 30 
lbs. of lean beef, and that as Baron Liebig once taught it is 
equal in nutritive value to this amount of beef. This extract 
lacks many of the most nutritious constituents, especially 
the proteids, and probably acts more as a stimulant and a 
substance to rouse the appetite for other foods, than as a 
true food. 2 There are also preparations on the market which 
consist of extract of beef, to which some of the meat fiber 
has been added. They are shown by analysis to contain 
some proteid. " Beef juices," which should be made by 
1 Loc. cit. 2 Church, " Pood," p. 183. 



NITROGENOUS FOODS 235 

expression of the juice from the raw or slightly heated meat, 
contain considerable proteid and are valuable nutrients. 

Eeferring to the fluid meat preparations, Thompson l says : 
"Usually they are tired of soon, and do not support life 
long, for, beyond the means employed of condensation of 
food by evaporation of water and compression, it is not 
possible to 'concentrate' nourishment very much. Making 
food assimilable and more useful is another matter from 
concentrating it in the sense that it can be made to sup- 
port an able-bodied man and supply him with energy for 
a day's work, for example, of mountain climbing." 

The different varieties of meat do not differ in their com- 
position as much as might be supposed. Some contain more 
water, some contain more fat. The fats, it will be remem- 
bered, belong to the same class as the carbohydrates; that is, 
they are " work and heat producers/' and not "tissue formers " 
like the nitrogenous foods. Comparative analyses show 
that when fat is deposited in a muscle, it replaces water, and 
not proteid, so the gain in nutritive matter is not attained by 
the loss of nitrogenous materials. Lean beef may contain 
19% of nitrogenous matter and 72% of water. Fat pork 
only contains 9.8% of nitrogenous matter and nearly 40% 
of water. Some of these foods are more digestible, of course, 
than others. For instance, mutton is said not to be as readily 
assimilated as beef. Veal is liable to produce intestinal 
disorders. Since fish 2 is both a cheap and nutritious food, 
it should be used, in many localities, in larger quantities than 
at present. The United States government is making praise- 
worthy efforts to introduce the common varieties of food 
fishes in all the waters of the country, so that fish may be more 
abundant and cheaper. If we compare the analysis of 
fish with that of meat, we notice that the nitrogenous part 

i " Practical Dietetics," p. 118. 

2 Bui. 28, Office of U. S. Dept. Agric. Exp. Stations. 



236 SANITARY AND APPLIED CHEMISTRY 

of fish affords more of the gelatin-yielding matter — that is, 
the collagen — and less extractives than meat. There is also 
much less haemoglobin in the flesh and blood of fish than 
in meat, so the flesh of most fish is of a light color. The 
mineral matter is usually high, and contains a considerable 
quantity of phosphates. Fish does not improve, like meat, 
by being kept, even on ice, but it rather deteriorates. 

Fish may be conveniently divided into two classes, — the 
lean and fat. Some examples of these are the following: 1 — 

Per Cent of Fat 

Fat Fish Somewhat Fat Lean 

Eels 18 Halibut .. 2 to 10 Cod ..... 0.4 

Salmon ... 12 Mackerel . 2 to 9 Haddock ... 0.3 

Herring ... 8 Mullet . . 2 to 3 Trout .... 2.1 

Turbot. ... 12 Bass .... 2.8 

There is more waste matter, such as skin and bones, in 
fish than in meat, and the per cent of water is very high, 
especially in the lean varieties. As fish contains con- 
siderable gelatin-yielding substances, it loses more on 
boiling than does meat, hence this is not a good method for 
cooking fish. 

Oysters are easily digested, but, as they contain 88% 
of water, they are not regarded as a valuable food from a 
purely nutritive standpoint. They contain both carbo- 
hydrates (glycogen) and nitrogenous matter, though it is 
probable that the latter is not all present in the form of 
proteids. Most of the other shellfish are not as digestible 
as oysters. 

Meats are liable to be dangerous to consumers on account 
of the diseases with which the animals have been affected. 
This is especially the case with pork, which is liable to be 
infected with tapeworms, trichinae, and other parasites. 
The only safe method to be employed, if we use pork, is to 
1 Farmer's Bui. 85, U. S. Dept. Agric. 



NITROGENOUS FOODS 237 

see that it is thoroughly cooked. Ham, for instance, unless 
boiled for a long time, is not heated to a high enough 
temperature to destroy the parasites. Most of the varieties 
of game are wholesome, and, where abundant enough to be 
reasonable in price, are very important foods. The same 
may be said of the so-called sea foods. ]\Iany of these 
furnish the proteid bodies in a very concentrated form, so 
if we use this kind of food exclusively, it is not a well- 
balanced ration. It is a familiar fact that sailors on 
long voyages or those living in nearly inaccessible regions 
suffer severely from scurvy if they are obliged to subsist 
on salt meats without potatoes or other vegetables. 

Experiment 124. Procure some " Hamburg steak, " and 
weigh out about 25 grams. Put this into 100 cc. of boiling 
distilled water and boil for 30 m. Keep the volume of 
the liquid constant by the addition of more water. Filter, 
while hot, through a cloth, and wash with hot water till the 
filtrate measures 200 cc. Evaporate this nitrate in a 
weighed dish, to dryness, cool, and weigh, and from this 
calculate the per cent of soluble matter obtained. 

Experiment 125. Weigh out a similar amount of steak and 
add to it 2 grams of salt. Carry out the experiment as in Ex- 
periment 124, subtract the 2 grams of salt from the weighed 
residue, and calculate the per cent of soluble material. 

Experiment 126. Weigh about 25 grams of steak, place it 
in a beaker in 100 cc. of cold water, and digest on a water 
bath at a temperature not above 80° C. (176° F.) for 2 hr., 
then filter, and proceed as in Experiment 124. Find the 
per cent of soluble material. 

Experiment 127. Weigh out 25 grams of steak, and treat 
as in the previous experiment, except add 2 grams of salt. 
Find the per cent of soluble material, after subtracting the 
2 grams of salt added. 



CHAPTER XX 

EGGS 

As the egg contains all the substances necessary for the 
development of the chicken, and to sustain it until hatched, 
its composition is of special interest. Over nine billions of 
eggs are produced annually in the United States (Clark) . 
Eggs contain much proteid and mineral matter, which is 
used to furnish the salts of the bones, especially calcium 
phosphate, and also fat, one of the most concentrated forms 
of nutriment. The average weight of a hen's egg 
is 60 g. (2 oz.), and of this the shell weighs 6 g., the 
white 36, and the yolk 18. The shell consists mainly of cal- 
cium carbonate. 

The white always has an alkaline reaction, and consists 
of a solution of proteid inclosed in numerous cells. When 
the egg is beaten the cells are ruptured and the proteid is 
set free. 

EGG WHITE 
According to Church 1 egg white has the following com- 
position : — 

Water 84.8 

Albumin 12.0 

Fat, sugar extractives, membranes . . . 2.0 

Mineral matter 1.2 

The nitrogenous material or albumin consists of at least 

four distinct compounds, all quite complex in structure. 

These contain carbon, hydrogen, nitrogen, sulfur, phosphorus 

i " Foods," p. 160. 

238 



EGGS 239 

and oxygen, but it is not at present possible to state their 

exact formulae. 

EGG YOLK 
The yolk is much richer than the white, as the following 

analysis shows : — 

Water 61.5 

Casein and albumin 15.0 

Oil, lecithin, etc. 30.0 

Pigment, extractive, etc. . . . . .2.1 

Mineral matter . .1.4 

The composition of the white and yolk together as com- 
pared with meat is as follows : 1 — 

Egg Modebately Lean Meat 
Water . . . . . 73.7 73.0 

Proteid 14.8 21.0 

Pat 10.5 5.5 

Ash 1.0 1.0 

So eggs may with propriety be used to supplement food 
rich in carbohydrates and lacking in proteids and fat. 
Fat ham and eggs do not form a well-balanced diet, but 
potatoes or bread with eggs form a good diet. It is esti- 
mated that from 15 to 20 eggs are the nutritive equivalent of 
2 lbs. of medium fat meat. 

For the preservation of eggs, a large number of methods 
have been proposed, such as packing in bran, coating with 
vaseline or gelatin, and covering with brine or limewater. 
The best method, however, has been found to be by covering 
with a 10% solution of water glass (sodium potassium 
silicate). 2 As these eggs break readily on boiling, they 
should be pierced with a needle before being put into the 
water. 

Desiccated eggs have been recently put upon the market. 
If fresh eggs are used in this preparation, there is no reason 

1 Atwater, Bui. 28, Office of Exp. Sta. U. S. Dept. Agric. 

2 Parmer's Bui. 103, Dept. Agric. 



240 SANITARY AND APPLIED CHEMISTRY 

why it should not be possible to furnish a good article of 
diet, when the water has been driven off by drying in 
thin layers, in a current of warm air. The temperature 
employed is one that will give as rapid drying as possible 
without coagulating the albumin. | A good quality of dried 
egg should contain 7% or less of moisture, 37% of fat, and 
about 30% of soluble, coagulable proteids. 

Most of the so-called "egg substitutes" and "custard 
powders" consist chiefly of starch, dried skimmed milk, and 
turmeric, a yellow coloring matter or Victoria yellow ; they 
are, of course, worthless as " substitutes." 

There is a popular notion that hard-boiled eggs are not 
digestible, and experiments made with eggs in the stomach 
lead to the same conclusion. Thus eggs slightly boiled have 
left the stomach in If hr., raw in 2\ hr., and hard-boiled in 
3 hr. It should be noted, however, that raw eggs are only 
partially digested in the stomach, perhaps because they do 
not excite the flow of the gastric juice. The complete diges- 
tion is accomplished farther along in the alimentary canal. 

In cooking eggs, especially for invalids, they should be 
placed in water at 170 ° to 180° F., and allowed to remain for 
10 m., when the yolk will be found to be more coagulated 
than the white. The egg albumin begins to coagulate at 
134° F., and it requires some time to heat the egg throughout. 

A convenient method for cooking eggs without the use of 
a thermometer, is to pour a quart of boiling water into a 
bowl, and put two or three eggs into this and allow them to 
remain for ten or twelve minutes. The yolk actually cooks 
more readily than the white, and by this process the eggs 
are cooked uniformly throughout. 

Experiment 128. Mix some egg white with water, add a 
drop or two of nitric acid, and notice that it coagulates. 

Experiment 129. Shake some egg yolk in a test tube 



EGGS 241 

with ether, decant off the clear liquid into a glass evaporat- 
ing dish and allow to evaporate spontaneously. The egg fat 
will remain in the dish. 

Experiment 130. To show the action of pepsin on eggs use 
0.1 gram of pepsin and 10 grams of boiled disintegrated 
egg albumin, that has been passed through a sieve. Make an 
acidulated water with 5 cc. of concentrated hydrochloric 
acid in 300 cc. of water. Dissolve the pepsin in 100 cc. of 
the acidulated liquid. To 5 grams of the disintegrated 
albumin, in a 100 cc. wide-mouthed bottle, add 25 cc. of the 
solution of pepsin and 40 cc. of the acidulated water. Cork 
the bottle and keep it in a water bath at a temperature of 
52° C. for an hour, and note the result. (L. E. Sayre.) 



CHAPTER XXI 



MILK 



In its composition milk suggests blood; that is, it is a 
thin watery fluid in which various bodies are held in sus- 
pension and in solution. We can readily see, by the use 
of the microscope, that the fat globules of milk are thus 
held in suspension. It has been shown that the richer the 
milk the larger these fat globules. The liquid that holds 
them in suspension is rich in nitrogenous matter and 
in sugar. As will be seen from an analysis, milk occupies 
an intermediate position between cereal and strictly animal 
foods. Of the cereal class, it contains milk sugar and 
fat; while of the animal class it contains casein and 
albumin. Milk is slightly alkaline in reaction. On account 
of the cost of milk in many cities, the poorer classes use 
only limited quantities. For instance, in London, an estimate 
made some time since showed from 1^ to 1\ oz. per capita was 
used weekly, while in Scotland &| pt. was used per week. 
The composition of milk from different animals varies con- 
siderably as can be seen by an inspection of the table: 1 — 





Spec. 
Gray. 


Water 


Casein 


Albu- 
min 


Total 
Proteids 


Fat 


Milk 
Sugar 


Ash 


Cow's 


1.0315 


87.17 


3.02 


.53 


3.55 


3.64 


4.88 


.71 


Human 


1.0290 


87.41 


1.03 


1.26 


2.29 


3.78 


6.21 


.31 


Goat's 


1.0305 


85.71 


3.20 


1.09 


4.29 


4.78 


4.46 


.76 


Sheep's 


1.0341 


80.81 


4.97 


1.55 


6.52 


6.86 


4.91 


.89 


Mare's 


1.0347 


90.78 


1.24 


.75 


1.99 


1.21 


5.67 


.35 


Ass's 


1.0360 


89.64 


.67 


1.55 


2.22 


1.64 


5.99 


.51 



1 Konig. 
242 



MILK 243 

The specific gravity of milk ranges from 1.027 to 1.035. 
A convenient form of apparatus to use in determining the 
specific gravity is the lactometer, which has a range from 
1.015 to 1.040, and is usually standardized at 60° F. (15° C.) 

Experiment 131. Test a sample of milk by a hydrometer 
or lactometer to determine its specific gravity. Readings 
taken at other temperatures than 15° may be corrected by 
a table that has been prepared. 

The lactometer was formerly relied upon to detect the 
addition of water to milk, but since the cream may be partially 
removed, and then considerable water added to correct the 
specific gravity, this instrument is not very valuable, ex- 
cept for confirmatory tests. 

By the saponification of butter fat the following compo- 
sition was obtained i 1 — 

Butyric acid 6.13 Oleic acid 36.10 

Caproic, caprylic, and capric Glycerol (calculated) . . 12.56 

acids 2 - 00 ISuJ2 

Myristic, palmitic, and stearic 

acids 49.46 

These results, and many others that might be quoted, 
show that butter fat is practically a mixture of various 
esters, those of butyric, palmitic, and oleic acids being the 
most abundant. The amount of stearic acid contained in 
butter is probably very small. The first four constituents 
are those which distinguish butter fat from ordinary fats 
like lard or tallow. It is by the determination of the 
amount of these that the chemist is able to distinguish 
between genuine butter and its imitations. 

The amount of fat varies from 3 % to 6.5 %, or even 7 %, 
in normal milk. In some countries any milk having less 
than 4 % of fat is considered adulterated, but the minimum 

1 James Bell, from Allen's " Commercial Organic Analysis," Vol. II, 
p. 181. 



244 SANITARY AND APPLIED CHEMISTRY 

amount allowed in many cities in the United States is 3 % . 
The Secretary of Agriculture in consultation with the Asso- 
ciation of Official Agricultural Chemists has adopted as a 
" standard " for milk, that it shall contain not less than 
12% of total solids, and not less than 8.5 °J of solids 
not fat, nor less than 3.25 °J of milk fat. The fat in milk 
can be separated for laboratory purposes by shaking it out 
with ether, and then allowing the ethereal solution to evapo- 
rate. A practical method for the determination of fat is 
the one used in large dairies ; that is, by the use of the 
Babcock tester. This instrument, invented by Professor 
Babcock of the University of Wisconsin, has proven of im- 
mense value to the dairy interests, as it is possible for the 
producer, as well as the manufacturer, to know exactly the 
value of the milk. The first milk, called the " fore milk," 
which is drawn from the udder of the cow, is poor in fat, 
because the fat globules have risen to the top ; but for the 
same reason, the " strippings," or last of the milk drawn, 
is rich in fat. 

The cream may be raised upon the milk by allowing it to 
stand in shallow pans for a long time, by putting it in deep 
vessels and keeping it at a comparatively low temperature, 
or more recently, and more practically, by the use of the 
" separator." This is nothing but a centrifugal machine so 
arranged that the lighter cream shall, when the milk is 
whirled with great rapidity, come to the center and be car- 
ried off by a pipe, and the heavier milk shall be thrown to 
the outside by the same motion, and carried off to a sepa- 
rate receptacle. 

There is a fermented beverage known as "koumiss," 
made from milk, which should be mentioned. It was 
originally prepared from mare's milk. It is made by mix- 
ing milk with yeast and some sugar, putting it in a bottle, 
and closely corking it. Fermentation takes place after 



MILK 245 

two or three days, and the beverage is fit for use. It is used 
as a nourishing tonic for invalids and seldom contains as 
much as 2% of alcohol. 

Experiment 132. Shake a few cubic centimeters of milk 
with ether, allow the ethereal layer to separate out, draw 
it off with a pipette, and allow it to evaporate on a watch 
glass. This gives quite a pure grade of butter fat. 

Experiment 133. Determine the amount of butter fat in 
several samples of whole milk by the use of the Babcock 
tester. By the action of oil of vitriol on a measured quan- 
tity of milk, a great amount of heat is evolved, and the 
mixture turns dark brown upon the addition of hot water ; 
when the bottle is put into a " centrifuge" and whirled 
rapidly, the fat, which is lighter, collects in the narrow 
stem of the bottle. The graduations of this stem have 
such a relation to the quantity of milk used that the per 
cent of butter fat can be read directly upon it. 

The total solid matter in milk is also of use to the 
chemist in forming an opinion as to whether a sample has 
been diluted with water or not. The lowest amount of 
solids usually permitted in normal milk is 12 %, but most 
milk contains from 1 to 3 % more. 

Experiment 134. Test the sample of milk, the specific 
gravity of which has been already determined (Experiment 
131) for " total solids," by weighing a small glass or porcelain 
evaporating dish on the horn-pan balance. Weigh into this 
about 5 cc. of the sample, and evaporate for about 2 hr., or 
till perfectly dry, on a water bath. Weigh the residue, and 
from this and the known weight of the milk, calculate the 
per cent of total solids. Eeserve the residue for Experi- 
ment 136. 

The casein of milk exists apparently in the fresh sample 
as a soluble compound of albumin and calcium phosphate, 



246 SANITARY AND APPLIED CHEMISTRY 

which by the action of " rennet," a ferment from the calf's 
stomach, is converted into an insoluble compound known as 
casein. The casein precipitate of rennet contains from 1 
to 1.5% of ash, consisting almost entirely of calcium phos- 
phate. Lactic acid also precipitates the casein, but the pre- 
cipitate contains less ash than that separated by rennet. 
Mineral acids also precipitate a casein containing less ash. 
The proportion of albumin in milk is always, according to 
Blyth, about one fifth of the casein. 

The proteids of milk contain about 80% of casein, which is 
not coagulated by heat but is coagulated by acids, about 15 % 
of lactalbumin, which is soluble and coagulates by heat and 
forms the skin on boiled milk, and a few minor ingredients. 

In the souring of milk, which is caused by certain acid- 
forming bacteria, part of the milk sugar is changed into 
dextrose and galactose, and the latter sugar changes to lac- 
tic acid: — 
C^B^OnjHgO = C 6 H 12 6 + CqKuOq. CeH^Og = 2C 3 H 6 3 . 

Lactose Dextrose Galactose Galactose Lactic acid 

This coagulates the casein, but when a certain degree of 
acidity is reached the ferment is killed, and the action stops. 
This suggests the change that takes place in wines (Chap. 
XXIII), for there also, as the alcohol increases, the ferment 
is destroyed. Coagulated milk is frequently used to make a 
kind of cheese which undergoes what is known as " butyric 
fermentation," producing an odor that by some is considered 
very disagreeable. 

After the casein has been separated from the milk by 
means of rennet, the whey, which remains, may be util- 
ized for making milk sugar. It is evaporated in a vacuum 
pan, purified by animal charcoal, and set aside to crystallize 
on sticks or strings that are hung in the vessel. The crystals 
have the formula C 12 H 22 O n ,H 2 0, and undergo lactic fermenta- 
tion readily, but alcoholic fermentation with difficulty. 



MILK 247 

Experiment 135. Treat a sample of skim milk in a test 
tube with just enough dilute HC1 to cause it to coagulate, 
keep warm for some time, and filter. Burn a little of the 
" curd " which remains on the filter, and notice, from the odor, 
its nitrogenous character. Neutralize some of the filtrate 
(the whey) with sodium hydroxid, and test it by Fehling's 
solution (Experiment 82) for milk sugar. 

The ash of milk consists essentially of phosphates and 
chlorids of potassium, sodium, calcium, and magnesium — 
salts that are especially needed for the growth of bone ma- 
terial in the young. A small quantity of citric acid is also 
found in milk in combination with lime. 

STERILIZED AND PASTEURIZED MILK 

Although milk which is drawn from a healthy, clean cow 
by clean hands into a bottle which has been sterilized is a 
sterile fluid, yet practically these conditions are not attained, 
and ordinary milk contains a variety of microorganisms. 
Some of these may produce souring and others may be bearers 
of disease. These organisms can be destroyed by a tempera- 
ture of 100° C, and a temperature of 75° C. will destroy most 
of the pathogenic bacteria. This process of heating is known 
as sterilizing, and although it is advocated for the treatment 
of milk for infants and invalids especially in large cities, 
yet the quality of the milk is decidedly altered. 

Some of the changes noticed in sterilized milk are : — 

1. A change of taste. 

2. The amylolytic ferment is destroyed. 

3. The fat is not so easily emulsified, and so cannot be 
so readily absorbed from the intestine. 

4. The casein does not coagulate so quickly, and there- 
fore is not as digestible. 

5. The lactalbumin is destroyed. 

On account of these changes produced by sterilization the 



248 SANITARY AND APPLIED CHEMISTRY 

method of Pasteurization has come into vogue, except in 
those cases where the milk must be kept for several days. 
Pasteurization consists in keeping the milk at a temperature 
of 167° F., for 20 minutes, instead of raising the temperature 
to the boiling point, as in sterilizing. By this process most 
of the bacteria that are liable to be present in the milk, are 
destroyed, the taste of the milk is not so much altered, and 
its nutritive qualities are not seriously interfered with. 
This milk will keep only one or two days under ordinary 
conditions. 

CONDENSED AND EVAPORATED MILK 

It is extremely convenient under some circumstances 
to have at our disposal condensed, or evaporated, milk. 
This may be made from " whole " milk or from skimmed 
milk, and it may or may not be preserved with cane sugar. 
There is one product on the market which is obtained by 
boiling the milk first in open pans and then in vacuum 
pans. This product is served to customers fresh, and will 
only keep for a few days. Another product, one which is 
more commonly used in the United States, is canned milk. 
This is made by boiling down the milk in a vacuum pan and 
mixing with cane sugar and sealing in the cans while hot. 
This product will keep for a long time, but not indefinitely, 
as it is liable, after a time, to become ropy and unfit for use. 

The unsweetened variety is often called " evaporated milk " 
or " evaporated cream." The latter, however, is usually noth- 
ing better than whole milk evaporated in a vacuum pan. 

According to a report of the Massachusetts State Board of 
Health, the following is the analysis of a normal condensed 
milk : total solids, 74.29% ; milk solids, 32.37% ; cane sugar, 
41.92% ; milk sugar, 11.37% ; proteids, 8.46% ; fat, 10.65% ; 
ash, 1.29% ; number of times condensed, 2.3. 

United States standard condensed milk should not contain 



MILK 249 

less than 28 % of milk solids, of which not less than one 
fourth is milk fat. Although it must be admitted that in 
some cases condensed milk can be digested more readily 
than fresh milk, yet in general its chief defect is that it con- 
tains too little fat ; that is, the dilution that is necessary on 
account of the large amount of sugar present, reduces the 
per cent of fat much below that of normal milk. 

One of the newest milk products on the market is "dried 
milk. " This product, as well as " dried cream/' is made by 
feeding continuously a thin sheet of milk between two 
steam-heated cylinders, revolving in opposite directions, 
and having a surface temperature above 100° C. The cyl- 
inders are slightly separated, and the milk is dried in 30 
seconds, and scraped from the rolls by a knife edge. The 
product is mixed with warm water for use. 

MODIFIED MILK 

From an inspection of the table given on p. 242, it 
will be seen that human milk differs from cow's milk in 
several important particulars. The latter contains a little 
less fat, considerably less sugar, more proteids, and more 
ash. On this account a great demand has arisen for cow's 
milk so modified that it shall approximate human milk in 
composition. The general method adopted to render 
common milk better adapted to the feeding of infants is to 
bring the proteids and ash to the right proportions by 
dilution with water, then to increase the per cent of sugar 
by the addition of lactose, and finally to add cream and 
usually some limewater. 

ADULTERATION OF MILK 

The most common adulteration of milk is by the addition 
of water, but the acid of milk is sometimes neutralized by 
the use of baking soda, or various preservatives may be 
added to it, especially in warm weather. 



250 SANITARY AND APPLIED CHEMISTRY 

Experiment 136. To detect sodium bicarbonate and borax 
in milk, the residue obtained in Experiment 134 is ignited 
to obtain the ash. After cooling, add a drop or two of 
HC1, and notice if there is any effervescence, which would 
denote the presence of carbonates. Test this acidified 
solution for borax by soaking in it, for a short time, a strip 
of turmeric paper, and allowing it to dry on the side of the 
dish above the solution. If the paper becomes of a dark 
cherry-red color when dry, and turns dark olive when 
treated with dilute sodium hydroxid solution, boric acid or 
borax has been added as a preservative. 

Experiment 137. To test milk for formaldehyde, use " For- 
maldehyde Eeagent, " which is made by adding to a liter of 
commercial hydrochloric acid (1.2 specific gravity) 2 cc. 
of a 10 % ferric chlorid solution. Ten cubic centimeters of 
this reagent is added to 10 cc. of milk in a small porcelain 
casserole, and the solution is heated, slowly, nearly to boil- 
ing, and at the same time a rotary motion is given to the 
vessel to break up the curd. When formaldehyde is present 
there will appear a violet coloration, especially when it is 
partially cooled. The color of this solution will vary with 
the amount of formaldehyde present. If this preservative is 
absent, the solution slowly turns brown. This test is said to 
be delicate to . * _ _ if the milk has not soured. With 

A o i (J U 

sour milk the limit of delicacy is 50 * . This test cannot 
be used when the milk is flavored with vanilla. 

CHEESE 

The general method of making cheese is by the addition 
of rennet to milk warmed to about 41° C. Eennet is the 
name given to an infusion in brine of the middle stomach of 
the calf. The rennet produces a coagulation of the milk by 
the action of an enzyme, which acts only in an acid or neutral 
solution. The coagulated milk, after having been broken 



MILK 251 

up several times in vats and heated to a moderate degree, is 
inclosed in cloth and the whey is pressed out. After the 
cheese has become solid, the molds are removed and the 
cheese is placed in well-aired rooms to cure. The flavor 
improves with age, from the development of fatty acids 
and ethers, and by the action of certain bacteria. A 
peptonizing enzyme has been recently discovered in milk, 
and to this is probably due the flavors that are induced 
in cheese during the process of ripening. As this process 
goes on, the cheese is turned daily and rubbed with oil. 
This improvement with age suggests what takes place in 
wines and liquors in the process of aging. Some yellow 
coloring matter, such as "annatto" or a coal tar dye, is 
frequently added to the cheese in the process of manufac- 
ture. Cheeses are generally classified as cream cheese, 
whole cheese, and skim-milk cheeses. 

Soft cheeses, like Brie, Neufchatel, and Cammembert, are 
made in a short time, and by coagulating with rennet at a 
low temperature ; i.e. below 30° C. 

Medium cheeses are allowed to drain for some time 
without pressure. The English " Stilton" and the Swiss 
"Gruyere" belong to this class. 

Hard cheeses, like "Cheddar," and the common cheese 
of the United States, is made by coagulating at a higher 
temperature — 30° to 35° — and then thoroughly pressing. 

The names applied to cheeses are frequently those of the 
locality from which they originally came. Limburger is a 
soft, fat cheese. Koquefort is made from the milk of the 
ewe. Parmesan is a dry Italian cheese, with a very large 
amount of casein, and a moderate percentage of fat. Edam is 
a Dutch cheese, quite dry, and having a red coloring on the 
outside. The following compilation by Woll 1 shows the 
average composition of some common varieties of cheese. 
1 Dairy Calendar, p. 223. 



252 



SANITABY AND APPLIED CHEMISTRY 





Watek 


Casein 


Fat 


Sugar 


Ash 


Cheddar 


34.38 


26.38 


32.71 


2.95 


3.58 


Cheshire 


32.59 


32.51 


26.06 


4.53 


4.31 


Stilton 


30.35 


28.85 


35.39 


1.59 


3.83 


Brie 


50.35 
44.47 


17.18 
14.60 


25.12 
33.70 


1.94 
4.24 


5 41 


Neufchatel 


2.99 


Roquefort 


31.20 


27.63 


33.16 


2.00 


6.01 


Edam 


36.28 


24.06 


30.26 


4.60 


4.90 


Swiss 


35.80 


24.44 


37.40 




2.36 


Full cream ( average ) . . . 


38.60 


25.35 


30.25 


2.03 


4.07 



It is evident that cheese is made up of about one third 
water, one third nitrogenous matter, and one fourth fat. The 
mineral matter is also of considerable importance. 

Cheese is so rich in nitrogenous matter, and also in fat, 
that it might properly form a valuable food for the poorer 
classes, while it is used by the more wealthy as a relish. A 
comparison with other animal foods shows very distinctly its 
theoretical value as food. It is rather difficult to digest 
in the stomach, unless finely grated or dissolved, as the fat 
protects the casein from the action of the digestive fluids. 
Protein and fat are often much cheaper in cheese than in 
meat. 

Eich cheese is very liable to decay, for it furnishes an 
excellent medium for the growth of living organisms. In 1884 
Dr. V. C. Vaughan isolated from cheese the poison, which 
he called tyrotoxicon.* This poison, which produces gastro- 
intestinal irritation and nausea, is developed in milk, ice 
cream, and cheese when the material is stored in dark, damp, 
filthy rooms or cellars, or where vessels used for holding 
the milk are not thoroughly cleaned for use. With proper 
care of the milk there is no danger of the development of 
this poison. 



MILK 253 

About the only falsification of cheese, aside from the 
fraudulent sale of skim-milk cheese for full-cream cheese, 
is the so-called " filled cheese/' which is made by working 
into the material in the process of manufacture some foreign 
fat, as oleo or lard. 

BUTTER AND BUTTER SUBSTITUTES 

Commercial butter is somewhat granular in appearance, 
and this is considered a very valuable quality of butter. It 
has a fragrant odor and an agreeable taste. It contains 
more or less casein, which causes it to undergo decompo- 
sition, if the butter has not been thoroughly washed. Butter 
must be salted in order to preserve it for any length of 
time. The composition of butter fat has been noted under 
the discussion of milk. The proportion of these different 
fats varies within slight limits only, and on this account 
it is not difficult to distinguish between natural butter and 
oleomargarin, or a butter that has been adulterated with 
other fats. Cream which is obtained by the use of the 
separator should be allowed to ripen for some time before 
it is churned into butter. In this process of ripening, 
certain bacteria take an active part, and to such a degree is 
this the case that the variety of bacteria in the dairy affect 
very materially the quality of the butter. Indeed it has 
become the custom in some dairies to import bacteria, or 
some material containing bacteria of a specially high grade, 
so as to make a fine quality of " June butter." 

On the continent of Europe the people purchase butter 
every day for that day's supply only, as the butter is never 
salted, and as it usually contains considerable buttermilk 
it will not keep. Butter has the average composition: 
water, 13.59%; fat, 84.39%; casein, .74%; milk, .50%; 
lactic acid, .12 %; and salts, .66 %. 



254 SANITARY AND APPLIED CHEMISTRY 

"Kenovated," or "Process," butter is, in general, made as 
follows : Old, rancid, and unsalable butter is melted in a 
large tank, surrounded by a hot- water jacket, at a temper- 
ature of about 45° C. The curd and brine are then drawn 
off at the bottom and the scum is taken off from the top. 
Air is blown through the mass, to remove the disagreeable 
odor, and, after mixing with some milk, the mass is churned, 
and then run into ice-cold water so as to make it granular 
in structure. The butter is then ripened, worked to free it 
from buttermilk, and salted. Some states require that this 
should be marked " Kenovated Butter " when exposed for 
sale, while others allow dealers to handle this product with- 
out restriction. 

The manufacture of artificial butter, butterine, or oleo- 
margarin has received encouragement, both in the United 
States and abroad, on account of the low cost, and also 
because the imitations are frequently better and more pala- 
table than low grades of cheap butter. The materials used 
in the manufacture of artificial butter are : " neutral " or 
leaf lard, from 25 to 60% ; oleo oil, from 20 to 50% : some 
vegetable oil, like cottonseed oil, from 5 to 25% ; milk or 
cream, from 10 to 20% ; butter, from 2 to 10 or 12% ; salt 
and annatto or aniline coloring matter. For different grades 
of oleomargarin different quanties of these substances are 
used. 

" Neutral " is made by melting leaf lard, and allowing it 
to " grain " by letting it stand at a temperature favorable 
for the separation of the stearin in coarse grains. Oleo oil 
is made in immense quantities, both for use in the manu- 
facture of butterine in the United States, and for shipment 
abroad. The process of manufacture is to cut the beef fat 
into small pieces and " render" it in water- jacketed kettles at 
the lowest possible temperature that is practical. The scum 
which separates at the top is drawn off and the scraps settle 



MILK 255 

to the bottom. The liquid fat is then run into vats, where 
it becomes partially cool. The semiliquid mass is wrapped 
up in cloths and pressed to remove the liquid oil from the 
solid fat. The solid fat, known as oleo-stearin, is used in 
the tanning and leather trades, by candle makers, for the 
manufacture of soap and of " compound " lard. The oleo 
oil is used in the manufacture of oleomargarin. 

For the manufacture of oleomargarin certain proportions 
of the ingredients, mentioned above, are churned and run 
into ice water to cool the mass rapidly, and then worked 
like ordinary butter. The particular variety made depends 
upon the market. The manufacturers exercise great care 
that the process shall be a clean one, and most authorities 
agree that a good quality of butterine is better than a bad 
quality of butter. 

At the instance of the dairy interests of the United States, 
however, a tax probably intended to be prohibitory has been 
levied upon butterine. This tax is very small, 1 cent per 
pound in case the butterine is not colored. If it is colored in 
imitation of butter, the tax is 10 cents. Until this law was 
passed at a recent session of Congress, the manufacture of 
butterine constantly increased, even though the industry 
was obliged to bear a small tax. In 1903 the total product 
of oleomargarin was but 71,237,438 lbs., while the previous 
year it was 123,133,852 lbs. 

Experiment 138. Place about 5 grams of butter in a small 
flask, add to it 30 cc. of a solution of potassium hydroxid 
in alcohol, and warm on a water bath. After the soap has 
had time to form, and while some alcohol still remains, add 
about 30 cc. of dilute sulfuric acid, and warm the solution. 
Notice the peculiar odor of butyric ether, especially if the 
solution is allowed to stand. 

Experiment 139. Foam test for purity of butter. Heat 
about 3 grams of the sample in a large iron spoon over a low 



256 SANITARY AND APPLIED CHEMISTRY 

Bunsen flame, stirring constantly. Genuine butter will 
boil quietly, with, the production of considerable froth or 
foam, which may, on removal from the flame, boil up over the 
side of the spoon. Eenovated butter or oleomargarin will 
sputter and act like hot fat containing water, but will not 
foam. Examine also the curdy particles when the sample 
is removed from the flame; in the case of genuine butter 
these particles are small and finely divided, bat in the case 
of oleomargarin the curd will gather in large masses. 

Experiment 139 a. To make the " milk " test for butter, 
place about 60 cc. of sweet milk in a wide-mouthed bottle, 
which, is set in a vessel of boiling water. When the milk 
is thoroughly heated, a spoonful of the butter is added and 
the mixture is stirred until the fat is melted. The bottle is 
then placed in a dish of ice water, and the stirring con- 
tinued until the fat solidifies. If the sample is butter, either 
fresh or renovated, it will be solidified in a granular con- 
dition and distributed through the milk in small particles. 
If, on the other hand, the sample consists of oleomargarin, 
it solidifies practically in one piece, so that it may be lifted 
by the stirrer from the milk. 

By the two tests just described, the first of which 
distinguishes fresh butter from process or renovated butter 
and oleomargarin, and the second of which distinguishes 
oleomargarin from either fresh butter or renovated butter, 
the nature of the sample examined may be determined. 1 

Experiment 140. To test for coal tar colors in butter, a 
small sample is mixed on a porcelain plate with Fuller's 
earth, and if they are present, there will be a red mass, 
while if absent the color will be only light yellow or 
brown. 

1 Bigelow and Howard, U. S. Dept. Agric, Bu. Chem., Bui. 100, p. 51. 



CHAPTER XXII 

BEVERAGES 

The ordinary beverages, not including milk, may be 
classified as nonalcoholic and alcoholic. 

NONALCOHOLIC BEVERAGES 

From the earliest time there has been a demand for some 
slightly stimulating beverage that is nonintoxicating in 
character. The simple herb drinks, such as catnip tea, 
sage tea, sassafras tea, etc., have been used and are more 
agreeable than hot water alone, which in itself is slightly 
stimulating. It is interesting to observe that in the very 
early history of the world, people, in different countries and 
under different conditions, selected certain plants which 
seemed to be stimulating in their effects, and made bever- 
ages from them. It was later found out that the plants 
so selected contain certain active principles which were 
stimulating in character. 

The most important of the beverages at present in use are 
tea, coffee, and cocoa. There is a growing demand for tea 
in the United States. The imports of tea for 1905 were 
96,779,145 lbs., valued at $15,003,588. The importation of 
coffee in 1905 amounted to 893,889,352 lbs., valued at 
$75,307,536. The importation of cocoa (crude) for 1905 
amounted to 79,722,791 lbs., valued at $8,965,387, besides 
923,127 lbs. of manufactured cocoa products. 1 The per 
capita consumption of these beverages in 1903 is reported, 

1 Bui. Dept. Com. and Labor. Dec. 1905. 
s 257 



258 SANITARY AND APPLIED CHEMISTRY 

for tea 1.30 lbs., for coffee 10.79 lbs. In Great Britain the 
per capita consumption of tea is four times that of the 
United States, while the per capita consumption of coffee is 
only one tenth that of the United States. 

TEA 

About 51% of our tea comes from China and 42% from 
Japan. The history of the discovery of tea is lost in antiq- 
uity. The first authentic account was as late as 350 a.d., 
while in European literature the earliest record appears in 
1550. The first consignment of tea into England took place 
in 1657, and it came into the United States in 1711. Genu- 
ine tea is prepared from the leaf of the Tliea sinensis, a 
plant which grows to the height of 4 to 5 ft. The leaves 
are ready for picking at the end of the third year, and the 
average life of the plant is about 10 yr. The leaves are 
picked at least three times per year, — in April, May, and 
the middle of July. The first pickings are the best and 
tenderest, and make the best grade of tea. 

PREPARATION OF THE TEA 

After sorting, the natural moisture is partially removed 
by pressing and rolling, then the leaves are dried by gently 
roasting in an iron pan for a few moments. They are then 
rolled on bamboo tables and again roasted, and finally sepa- 
rated into the various grades by passing through sieves. 

The difference between green and black tea is mainly 
due to the fact that the green is steamed thoroughly and 
then rolled and carefully fired, whereas black tea is first 
made up into heaps which are exposed to the air and al- 
lowed to ferment, and thus the olive-green is changed into 
a black color. 

In the preparation of Japan tea, the leaves are steamed 
in a tray over boiling water. They are then heated on a 
tough paper membrane over an oven and at the same time 



BEVERAGES 259 

stirred with the hand. The tea after being thus fired 
is dried for some hours and sorted by passing through 
sieves. Then it is sent to the warehouse, where sometimes 
the "facing process" is carried on, by heating the tea in 
large bowls and adding various pigments to it. 

There are but few spurious teas on the market, but the 
range in quality is very great. On account of the strict 
enforcement in the United States of the adulteration act, 
no adulterated tea is permitted to be imported, and the con- 
sumer is reasonably well protected. He usually secures 
genuine leaves though he may get very inferior grades of tea. 

Tea, as prepared for the foreign market, is exposed to a 
large number of sophistications and adulterations, mainly 
for giving it an increased weight. These adulterations 
include adding foreign leaves, spent tea leaves, metallic 
iron, sand, brick dust, etc. 

Again, substances, such as catechu or similar materials 
that contain tannin, are added to produce an artificial 
appearance of strength. Another sophistication, which is 
practiced especially on green tea, consists in imparting a 
bright appearance to inferior tea by means of coloring mat- 
ter or facing ; for this purpose they use soapstone, gypsum, 
Prussian blue, indigo, turmeric, and graphite. Another 
form of sophistication is practiced on exhausted tea leaves 
by a similar process of facing. It is even said to be possi- 
ble, by careful manipulation, to change black tea to green 
and vice versa. 

The Indian teas are very much stronger than those from 
China and Japan, so that they produce a beverage that seems 
too strong to those accustomed to Chinese and Japanese teas. 
The Indian teas only come in contact with the hands of the 
workmen at the time of picking. The Chinese teas are 
manufactured almost entirely by hand, although sometimes 
the feet are used in rolling the cheaper grades. 



260 



SANITARY AND APPLIED CHEMISTRY 



A substance called " lye tea " is frequently put upon the 
foreign market. This consists of fragments of genuine leaves, 
foreign leaves, and mineral matter held together by a starch 
solution and colored with various preparations. It is prob- 
able that the addition of foreign leaves is but little 
practiced at the present time in the United States. 

In England black teas are used much more than the 
green. This is due to the supposition that black teas con- 
tain less astringent matter and also act less upon the nerves. 
By comparison of analysis of black and green tea it is evi- 
dent that there is less material soluble in hot water in the 
former. 1 





Green Tea 


Black Tea 


Crude protein .... 


37.43 


38.90 


Fiber 


10.06 


10.07 


Ash 


4.92 


4.93 


Thein 


3.20 


3.30 


Tannin 


10.64 


4.89 


Total nitrogen .... 


5.99 


6.22 



The important constituents are the extract, a certain 
amount of tannin and thein, and the volatile oil. On account 
of the presence of a large amount of tannin in tea, which is 
extracted by heating with water, it is important, in making 
the beverage, that the water should not stand for any 
length of time upon the leaves. On this account a much 
more wholesome beverage may be made by the use of the 
tea-ball with the hot water. It is a great mistake to allow 
the tea to draw, as the saying is, for hours at a time. 
Freshly boiled water should be used in making tea, and 
it should be thoroughly boiling when poured upon the 
leaves, and allowed to digest about three minutes, not 
1 Analysis by Kozai : W. G. Thompson, " Practical Dietetics," p. 211, 



BEVEBAGES 261 

longer. Longer infusion will make the tea appear stronger 
but will spoil its delicate flavor, and extract too much tannin, 
which will have an injurious effect on the system. The 
water used should not be too soft, as that will extract 
more soluble material, nor should it be extremely hard. 
The thein is practically all extracted from tea within the 
first five minutes, while the amount of tannin continues 
to increase for 40 minutes or more. The infusion should 
be poured off from the grounds as soon as made. 

According to Hutchison an ordinary cup of tea will con- 
tain nearly a grain of thein, and from 1 to 4 grains of 
tannin, dependent on the kind of tea used. There is no 
direct relation between the quality or price of the tea and 
the proportion of thein. This substance, thein, which has 
the formula C 8 H 10 N 4 O 2 , is an ureide belonging to the same 
general class as guaranin, xanthin, uric acid, etc. The vola- 
tile oil which is present gives to the tea its agreeable flavor 
and aroma. 

Experiment 141. Make a decoction of tea in a test tube, 
pour it off from the grounds, and test a part for tannic acid. 
First, by ferric chlorid ; 
Second, ferrous sulfate ; 
Third, by a mixture of the two reagents. 
A black or bluish black color (ink) will be produced. 

PARAGUAY TEA 

There is another variety of tea known as Paraguay tea, 
or Yerba Mate, which was selected by the people of South 
America to use as a beverage. This tree grows wild, and is 
known to the botanist as Ilex paraguayensis. The tea 
is prepared in Paraguay by cutting off the small twigs and 
leaves and placing them on a clean plot of earth surrounded 
by fire. In this way the leaves are wilted and cured, and 
they are afterward dried on a grating over a fire, and then 



262 SANITARY AND APPLIED CHEMISTRY 

reduced to a coarse powder. The infusion, which is pre- 
pared in a kind of gourd, is conveyed to the mouth by 
means of a reed or a silver tube called a "bombilla," with 
a strainer at the end. 

Mate contains 1.3% of thein and 16% of tannic acid, also 
an aromatic oil and gluten. The tannic acid has entirely 
different properties from that contained in tea or coffee. 

COFFEE LEAF TEA 

In some coffee-growing countries the natives use the 
leaves of the coffee tree to make an infusion which has about 
the same constituents and properties as ordinary tea. 

COFFEE 

Coffee is the seed of the Coffea arabica, indigenous in 
Abyssinia and Arabia, and this plant, at the present time, is 
grown in Java, the West Indies, in Ceylon, Mexico, and 
Central and South America. It was used in the remotest 
time in Arabia. It was introduced into Constantinople in 
1574; in 1660 it was carried from Mocha to Java, and 
thence specimens of the tree were taken to Holland and 
France. Coffeehouses were opened in London about the 
middle of the seventeenth century. In 1809 the first cargo 
was shipped to the United States. There is a great difference 
in the quality and flavor of coffee from different localities. 

The coffee tree is productive for about thirty years. The 
trees are usually planted every twenty years and grow 
best on the uplands. The trees are raised from seeds 
in nurseries and transferred to the plantations. In Java 
the picking of the berry begins in January, and lasts 
three or four months ; in Brazil, the picking begins in April 
and May, and continues throughout the season. After 
the berries are harvested, the first operation by which they 
are treated is called pulping. Sometimes the berries are 



BEVERAGES 



263 



pulped in the soft state, sometimes they are first dried, and 
then the dried skins are removed by a machine called a 
huller. The West India and Brazilian method is to macer- 
ate the berries in a large vat, where they are treated 
by what is known as a pulping machine, which is an iron 
cylinder set with teeth, which removes the outer covering. 
The loosened pulp is carried out at one side and the berries 
sink to the bottom of the vat. The berries are afterward 
dried, cleaned, and sorted. 

The next process is the roasting of the bean. This may 
be carried on directly over a fire or in an oven. The average 
loss of weight in the process of roasting is about 16%. 
This process develops an essential oil and brings out the 
aroma of the coffee. If the operation is carried too far, 
the best properties and ingredients are lost. 

The following analysis by Konig shows the difference be- 
tween raw and roasted coffee : — 



Eaw 
Coffee 


Roasted 

Coffee 


11.23 


1.15 


1.21 


1.24 


12.27 


14.48 


8.55 


.6G 


18.17 


10.89 


12.07 


13.98 


32.58 


45.09 


3.92 


4.75 



Water 

Caffein 

Fat 

Sugar 

Cellulose 

Nitrogenous substance . . 
Other non-nitrogenous matter 
Ash 



The effect of roasting is to drive off a large part of the 
water, and to caramelize most of the sugar. The bean 
becomes more brittle, and the caffeol 1 (C 8 H 10 O 2 ), to which 
coffee largely owes its odor and flavor, is, at the same time, 

1 Hutchison, "Food and Dietetics," p. 310. 



264 SANITARY AND APPLIED CHEMISTRY 

developed. The active principle, called them, or caffein 
( C 8 H 10 ;N" 4 O 2 ), is believed to be identical with that of tea. The 
infusion of coffee also contains some nitrogenous material. 

Ground coffee is especially liable to be adulterated. 
Some of the chief substances added to the commercial ground 
coffee are chicory, caramel, peas, and roasted grains, such as 
corn, wheat, and rye. There has also been found upon the 
market an artificial coffee bean which contains absolutely no 
coffee, and is made by compression of harmless, starchy ingre- 
dients into the form of the coffee bean. This is mixed with 
the genuine beans. The raw coffee bean is sometimes sub- 
jected to the process of sweating, by which it is increased 
in size and improved in color and flavor ; it is sometimes 
moistened with water containing a little gum and colored 
with various pigments, such as Prussian blue and turmeric, 
so as to improve its appearance. In this way, for instance, 
Mexican coffee is made to resemble Java coffee. 

In regard to making the beverage coffee, there are two 
methods, either of which may be used. The first is to put 
ground coffee into cold water and bring the decoction to the 
boiling point. The second, and probably better, method is to 
have the water boiling tumultuously and add to it the required 
amount of finely ground coffee, boil not more than three 
minutes, and then serve immediately. If the coffee is 
allowed to boil for any length of time, not only is the tannin 
extracted from the berry, but the agreeable aroma and 
flavor is lost, as it is carried off with the volatile oil. The 
coffee is then not as wholesome, and it certainly is not as 
agreeable in flavor. 

Many persons find that black coffee produces less ill-effects 
upon the system than does coffee served with cream. This 
may be due to the compound produced by the action of the 
tannin of the coffee upon the proteid substances of the milk. 
Cafe au lait, which is a mixture of three parts of hot milk 



BEVERAGES 265 

with one part of coffee, is a popular beverage in many 
countries. It will be noticed that coffee contains less of 
the alkaloid than tea. 

There are many varieties of coffee upon the market, but 
the Mocha and Java coffees usually command the highest 
price. The low grades of coffee have decreased very much 
in price during the last few years. This is probably due 
to the competition, and, also, to the fact that immense quan- 
tities of the cheaper grades are raised in South and Central 
America. The latest official report (1905) shows that three 
fourths of the coffee imported into the United States comes 
from Brazil. The coffees range in price from 8 cents to 45 
cents per pound at retail. Some persons have become accus- 
tomed to the strong black coffee made from the Eio brand, 
and to meet their demand, in " blending," some Eio is often 
added to other grades. 

There is no great objection to the substitutes for coffee 
that are upon the market, if they are not bought as coffee. 
Many of these are no doubt wholesome enough, and if 
coffee has been found to disagree with the system, it is 
probably better to use some beverage of this kind, which 
is simply an extract of a roasted cereal. 

COCOA AND CHOCOLATE 

The raw material from which cocoa and chocolate is made, 
is the seed of the Theobroma cacao. It grows most readily 
from Mexico to Peru on the west coast of the American 
continent, in Mexico and Brazil on the east coast, and in 
the West India Islands. It was introduced into Europe by 
the Spaniards in 1519. Chocolate was first prepared in the 
United States in 1771, at Dan vers, Mass. 1 The tree is about 
18 or 20 ft. high, blooms continuously, and yields two crops 
a year. The lemon-yellow fleshy fruit is about 7 in. long, 
1 Harrington, " Practical Hygiene," p. 174. 



266 



SANITARY AND APPLIED CHEMISTRY 



something like a short cucumber in appearance, and has ten 
longitudinal ridges. The seeds are arranged in five rows 
in the pulpy flesh. There are two processes for preparing 
the seed for the market. For unfermented cocoa the seeds 
are separated from the pulp and dried in the sun ; for the 
fermented cocoa the seeds are placed in piles and allowed 
to ferment, before being dried. Much of the acridity and 
bitterness disappears in this process of fermentation. The 
principal operations in the process of manufacture are, first, 
the sifting of the raw cocoa to remove the sand and dust ; 
second, the separation by hand of the larger stones and empty 
pods, etc. ; third, roasting the cleaned seeds. 

The following table l shows the composition of some cocoa 
products : — 



"Water 

Ash 

Theobromin 

Caffein 

Other nitrogenous substances 

(protein) 

Crude fiber 

Sugar 

Pure starch 

Other nitrogen-free substances 
Eat 



o -< 3 

H O « 2 

« O H ^ 

U X >< 



3.78 
3.15 

.78 
.13 

12.36 

2.86 

18.11 
16.64 
52.19 



E- 1 fa 2 
H S ° <° 

Pgss 

03 ri < * 

£S5s 



2.17 

1.40 

.35 

.08 

4.58 
.95 

56.44 
2.88 
7.64 

23.51 



g K >* 
O O ^ 

H - fc 



6.23 

5.49 

1.15 

.16 

18.34 
4.48 

11.14 
26.32 
26.69 



5 S H ^ 



4.87 

10.43 

.49 

.16 

14.46 
16.55 

4.13 

46.15 

2.76 



Cocoa is not only used to make a pleasant and exhilarat- 
ing beverage; it is a valuable food material. The most 



Rep. Conn. Agric. Exp. Station, 1903, Pt. II, p. 125. 



BEVERAGES 267 

important constituents are fat, theobromin, which is the 
alkaloid or, properly speaking, the ureide of cocoa, a little 
starch, and some albumin and fibrin. The fat usually forms 
about 50 % of the husk and bean. It is a mixture of the 
glycerides of stearic, palmitic, lauric, and arachidic acids, 
and is extensively used in pharmacy under the name of 
" cocoa butter " Theobromin, which was discovered in 1841 
by Woskresensky, is very closely related to xanthine, being 
dimethyl xanthine, C 5 H 2 (CH 3 ) 2 lSr 4 02' Caffein is trimethyl 
xanthine, C 5 H(CH 3 ) 3 ]Sr 4 2 - 

The commercial preparations of cocoa are quite numerous. 
Plain chocolate is prepared by grinding roasted and husked 
seeds to a paste and pressing in the form of cakes. When 
this is combined with sugar, vanilla, etc., sweet chocolate is 
the product. Since there is so much fat in the cacao, this is 
frequently partially removed, and the residue is put on the 
market under the name of cocoa. Cocoa shells or husks are 
sometimes used for making an exceedingly weak beverage of 
this class, which contains little fat, but considerable nitrog- 
enous matter and extractives. Cocoa "nibbs" are the 
bruised, roasted seeds freed from the hardened grains, and 
contain all the fat. The names that are applied to the differ- 
ent preparations of cocoa and chocolate vary in different 
countries. Cocoa and chocolate preparations are very readily 
adulterated, but, after all, the general adulterants, if such 
they may be called, are sugar and starch, which are not 
injurious, but only decrease the cost for the benefit of the 
manufacturer. The genuine chocolate should contain all 
the original fat. An inferior vanilla chocolate is flavored 
with the artificial vanillin and coumarin in place of the 
finer flavored vanilla bean. 

It is said that the term " soluble cocoa " is erroneous, as 
very little of the albuminous substances or the fat are solu- 
ble. In order to grind the bean to a very fine powder it 



268 SANITARY AND APPLIED CHEMISTRY 

must be mixed with sugar or starch, and this, in fact, is the 
method used in the preparation of some of the powders rec- 
ommended for invalid diet. Sometimes, in order to make 
a cocoa that shall be more digestible, a part of the fat is sa- 
ponified by the use of sodium hydrate and magnesia, a pro- 
cess that may in some cases produce a food that is less 
digestible than the material that is not so treated. 

Sweet chocolate, especially by reason of the sugar that is 
added, has a high food value. Chocolate does not, like tea 
and coffee, produce wakefulness, though, on account of the 
large amount of sugar and fat which it contains, it may pro- 
duce indigestion. As chocolate is a concentrated food, it 
may be conveniently used when the weight of food to be 
carried must be considered, as on the march, or on camping 
expeditions. 

Experiment 142. Shake a few grams of powdered chocolate 
in a test tube with ether, filter, and allow the filtrate to evap- 
orate spontaneously in a glass evaporating dish. Notice the 
taste and odor of the fat or " cocoa butter " that remains. 
Notice also that cocoa butter gives a clear solution with 
ether, while wax or tallow gives a turbid solution. 

Experiment 143. Boil a few grams of powdered chocolate 
with water, filter off 10 cc, and treat the cold solution with 
iodine reagent for starch. 

COLA 

The cola nut grows on a small tree in several tropical 
countries especially Jamaica, Africa, East India, and Ceylon. 
It contains caffein, theobromin, tannin, and the other con- 
stituents of tea and coffee. As a beverage it is made into 
an infusion like coffee, and is served with milk and sugar. 



BEVERAGES 269 

COMPARISON OF THE COMMON STIMULATING 
BEVERAGES 

These beverages possess qualities in common for which 
they are universally esteemed by mankind. First, they re- 
tard the retrograde metamorphosis of the body tissues, and 
thus enable the work of the individual to be done upon a 
smaller supply of food material and with less fatigue. 

Second. When used in moderation, they are all more or 
less stimulating to the mental powers. 

Third. They act as sedative to the nervous system. The 
similarity of the action of these beverages is due to the pos- 
session of common constituents. While there are diver- 
gences from each other, in their finer shades of action their 
value depends upon the aromatic and volatile oil which modi- 
fies the action of the alkaloid. It is an interesting fact that 
similar properties are developed in each of them by roast- 
ing and drying. 

Coffee is more stimulating than cocoa. It is apt to cause 
irregularity and palpitation of the heart and may disorder 
digestion if boiled too long. 

Tea is the most refreshing and stimulating of these bev- 
erages. Used in excess, however, it powerfully affects sta- 
bility of the motor and vasomotor nerves, the action of the 
heart and the digestive functions, producing dyspepsia, 
tremulousness, irregular cardiac action, headache, etc. 

Mate is supposed to be intermediate in its effects between 
tea and coffee. Chocolate is more nutritious than tea or 
coffee on account of the amount of fat which it contains ; 
although much of this fat is removed in making cocoa. 
Since but little of the solid is used in making the beverage 
cocoa or chocolate, the food value is not very great. Cocoa 
and chocolate are only slightly stimulating in their effects. 

Cola probably has a restraining influence on tissue waste 



270 SANITARY AND APPLIED CHEMISTRY 

and is mildly stimulating to the heart and nervous system. 
As it will increase the endurance, it may be used when 
severe muscular exercise is to be undertaken. 

When we consider the whole subject of beverages of this 
class, it is extremely interesting to notice that uncivilized 
people and civilized people in different ages of the world, in 
different climates, and under entirely different circumstances, 
have chosen plants to use in the manufacture of beverages 
that contain these alkaloid principles ; caffein in the case 
of tea, coffee, and cola, and theobromin in the case of choco- 
late. Most of them also contain the astringent principle 
tannin. The use of these beverages has increased from year 
to year in all civilized countries. 



CHAPTER XXIII 



ALCOHOLIC BEVERAGES 



It is probably true that alcohol, as such, is not found in 
sound fruit, yet alcohol is so readily formed by the process of 
fermentation of sugar, that it was not strange that it was 
accidentally discovered, and that beverages having intoxi- 
cating qualities should have been used very early in the 
history of the world. Alcohol, C 2 H 5 OH, is a colorless 
liquid, having an agreeable odor, burning with a blue flame, 
and having a specific gravity of .792. Ordinary alcohol is 
about 95 % strength, and the remaining 5 % is water. 
Proof spirit, as it is called, contains 42.50 % of alcohol by 
weight or 50 °J by volume. This was originally named from 
being the most dilute spirit which when lighted would fire 
gunpowder. 

The annual consumption of alcoholic beverages, per cap- 
ita, in the United States, and in several other countries, in 
1900, was : — 





G-ALLON8 




Beer 


Wine 


Spirits 


England . . 

France «... 


30.31 

5.10 

25.50 

12.30 


.39 

21.80 

1.34 

.44 


1.02 
1.84 


Germany 


1.84 


Japan, all liquors (mostly sake") . . . 
United States 


6.25 

.84 







271 



272 SANITARY AND APPLIED CHEMISTRY 

The Statistical Abstract of the United States for 1903 
reports the per capita consumption of distilled spirits to be 
1.46 proof gal. ; that of wine, 0.48 gal. ; and that of malt 
liquors, 18.04 gal. There is a notable increase in the con- 
sumption of malt liquors from year to year. 

Alcoholic beverages may be made from any vegetable 
product that contains starch or sugar. There are four 
general classes, viz.: — 

1. Fermented liquors : as wine, cider, perry ; wine from 
fruits, berries, etc. ; palm wine, called " toddy " in India ; 
bouza, made in Tartary and the East from millet seed; 
honey wine, used in Abyssinia ; koumiss, made from mare's 
milk in Tartary ; fig wine, made in the vicinity of the Medi- 
terranean Sea ; and pulque, made by the Mexicans from the 
juice of the century plant. 

2. Malt liquors : as lager beer, ale, porter, stout ; kvass, 
made in Eussia from rye ; chica, made in South America 
from corn, rice, etc.; sake, made in Japan from rice; and 
pombe, made in Africa from rice. 

3. Distilled liquors : as alcohol, whisky, brandy, gin, and 
rum, and vodka made from grains in Eussia, arrack made 
from rice and palm juice in India, mescal or pulque brandy, 
and cherry brandy, or " Kirsch-wasser," as it is termed, 
in Germany. 

4. Liqueurs and cordials : as absinthe and vermuth. 
The fermented liquors are made from the juices of fruits, 

which contain sugar, and they require no yeast to start the 
fermentation, but depend on the germs which are present in 
the natural juices. Most of the sugar present in fruits is in 
the form of invert sugar. As the quantity of alcohol that can 
be obtained from any fruit juice is dependent on the amount 
of sugar contained, a consideration of the sugar content is 
important. 



ALCOHOLIC BEVERAGES 



273 



The following analyses, by Fresenius, show the amount 
of sugar and acid in the common fruits : — 



Grapes . . . 

Sweet cherries . 

Sour cherries . 

Mulberries . . 

Apples . . . 

Pears . . . . 
Gooseberries 
German prunes 

Currants . . . 
Strawberries 
Blackberries 

Raspberries . . 

Green grapes . 

Plums . . . . 

Apricots . . . 

Peaches . . . 



Per Cent 
Sugar 


Per Cent Free 
Malic Acid 


16.15 


.80 


15.30 


.88 


10.44 


1.52 


10.00 


2.02 


9.14 


.82 


8.43 


.09 


8.00 


1.63 


7.56 


1.08 


7.30 


2.43 


6.89 


1.57 


5.32 


1.42 


4.84 


1.80 


4.18 


.67 


2.80 


1.72 


2.13 


1.25 


1.99 


.85 



WINE 

The most important of the fermented beverages is wine. 
The cultivation of grapes, for the purpose of making wine, 
began in the East in the earliest times, and extended along 
the shores of the Mediterranean Sea. Germany, Austria, 
France, Italy, Spain, and Portugal are the continental wine- 
growing countries, while in the United States the industry 
is of great importance in Ohio, New York, Virginia, and 
California. The quality of the wine depends on the variety 
of grapes, the soil, climate, and even on the weather. 

In order to make genuine wine, the grapes are allowed 
to ripen, so that they contain as much sugar as possible. 
The grapes are carefully crushed and pressed, and the first 
juice that runs off produces the best quality of wine. The 



274 SANITARY AND APPLIED CHEMISTRY 

" marc," as the pulp is called, is sometimes pressed several 
times after being soaked with water, and this affords cheaper 
qualities of wine. The " must," as the pressed juice is called, 
is allowed to ferment from 10 to 30 days. Fermentation be- 
gins at from 10° to 15° C, and is brought about by the germs 
which grow at the expense of the saccharin and albuminous 
substances present, and change the sugar to carbon dioxid 
and alcohol. Thus : — 

C 6 H 12 6 = 2C 2 H 6 + 2C0 2 . 

Sugar Alcohol Carbon dioxid 

After the first fermentation, the wine is drawn off from 
the "lees" and put in casks, where the after fermentation 
takes place. The " lees " consist of the fungus growth, some 
calcium salts, coloring matter and "argols," potassium 
bitartrate, or " cream of tartar," which is insoluble in dilute 
alcohol. This is the only practical source of cream of tartar ; 
consequently this chemical commands a good price. 

From 60 lb. to 70 lb. of "must" can be obtained from 
100 lb. of grapes. The quantity of sugar in the juice va- 
ries from 12 to 30%. It is of importance that the ferment 
be of a certain kind to produce a good wine ; and, indeed, 
the bacteriologist has begun to propagate special cultures of 
a pure yeast to produce wine of a desired flavor. The wine 
is stored in casks for some months, for the process of aging. 
Before being placed in the cask, the wine is treated with 
isinglass, or egg albumen, and " racked off " from the depos- 
ited impurities. It must not be too freely exposed to the 
air, as there is danger that the alcohol, by the aid of the 
acetic ferment, shall be changed to acetic acid, according 
to the reaction, — 

C 2 H 5 OH + 2 2 = C 2 H 3 O.OH + 2 H 2 0. 
During the aging process a variety of fragrant ethers, as 
acetic ether, malic ether, etc., are formed, which produce 
an agreeable odor or bouquet. Wines are sometimes aged 



ALCOHOLIC BEVERAGES 



275 



and at the same time preserved, by pasteurization, which 
consists in heating them for some time at 60° C, with a 
limited supply of air. 

In regard to the changes that take place in the cask, 
Leach observes that the alcoholic strength of the wine rises. 
This is due to the fact that the water of the wine soaks into 
the wood more than the alcohol does, and is lost by evapo- 
ration, so that the wine becomes more concentrated. As 
the water so lost is replaced by the addition of more wine, 
the increase in the proportion of alcohol is rendered all the 
greater. In the cask, too, a partial oxidation of the tannic 
acid takes place. This causes the white wines to become 
darker in color, but has just the reverse effect upon the red 
wines ; for the oxidized tannic acid unites with and precipi- 
tates some of the pigment. 

The alcoholic strength of the wine is somewhat increased 
by a further fermentation of the sugar. By the oxidation 
of some of the alcohol to acetic acid, compound ethers are 
formed. There is an impression that wine continues to im- 
prove with age, and " old wine " is highly prized. Some of 
the stronger wines improve for a few years, but not for an 
indefinite time, and wines often begin to deteriorate after a 
short time. The " extract," as the term is used below, is 
what remains upon evaporation. 

The following table gives the composition of a few 

wines : — 

Composition of Wines 





Alcohol 


EXTEACT 


Fkee Acid 
Taktaeic 


SUGAE 


Ash 


French red 


7.80 


2.97 


.58 


.46 


.25 


French white 


10.84 


1.26 


.44 


.88 


.20 


Spanish red 


12.34 


3.84 


.57 


.25 


.75 


Calif, red 


10.03 


2.11 


.64 


.25 


.34 


Calif, white 


11.16 


11.80 


.63 


.20 


.17 



276 SANITARY AND APPLIED CHEMISTRY 

Sweet Wines 





Alcohol 


EXTRACT 


Free Acid 
Tartaric 


Sugar 


Ash 


Champagne . 
Port .... 
Sherry . . . 
Madeira . . 


9.60 
16.29 
15.93 
16.49 


14.34 
8.30 
6.00 
6.61 


.58 
.38 
.48 
.41 


.75 
6.26 
2.76 
3.18 


.16 
.25 
.56 
.33 



CLASSIFICATION OF WINES 

Wines are either natural or "fortified." Natural wine 
contains no added alcohol or sugar. When the pure juice of 
the grape is allowed to ferment, if it contains sufficient 
sugar, the amount of alcohol will continue to increase till 
the wine contains about 15%, and this amount of alcohol 
prevents any further fermentation. Hock and claret are 
usually of this class. When alcohol is added to the wine 
it is said to be "fortified." Port and Madeira are often 
treated in this way. 

Wines are divided into red and white wines, from the 
color ; also into dry wines, or those in which all the sugar 
has been changed to alcohol ; and sweet wines, or those in 
which some sugar still remains, although these are often 
reinforced by the addition of grape sugar. Dry wines are 
consequently slightly sour. Wines are also divided into 
"still" wines, or those in which the carbon dioxid gas 
has been allowed to escape ; and effervescent wines, in 
which the carbon dioxid has been retained in the liquid 
under pressure. 

Grapes make better wine than other fruit because the 
potassium bitartrate (KHC 4 H 4 6 ) is precipitated as the 
alcohol becomes stronger in the process of fermentation. 
Other fruits and berries, on the other hand, contain citric, 
malic, or succinic acids, and the salts of these are not pre- 



ALCOHOLIC BEVERAGES 277 

cipitated during fermentation, and so this wine has not the 
agreeable taste that characterizes grape wine. 

ADULTERATION OF WINES 

The adulterations of wine are very numerous. Plaster of 
Paris is often used abroad for the adulteration of wines, but 
native wines and those imported into the United States are 
usually free from this material. This is done, it is said, to 
clarify it, to improve the color, to make the fermentation 
more complete, and to improve the keeping qualities. On 
the other hand, this process is supposed to leave some 
injurious compounds in the wine. The reaction due to 
"plastering" is as follows : — 

2 KHC 4 H 4 6 + CaS0 4 = CaC 4 H 4 6 + H 2 C 4 H 4 6 + K 2 S0 4 . 

Pot. bitartrate Cal. sulfate Cal. tartrate Tartaric acid Pot. sulfate 

In Prance there is a law against the addition of more than 
a limited quantity of plaster of Paris to wines intended for 
home consumption. Not over .2% of potassium sulfate is 
allowed to be present. The wine manufacturers also burn 
sulfur in the casks so that the sulfur dioxid shall artifi- 
cially age the wine. This tends to decrease the number of 
germs that would be injurious in fermentation. The addi- 
tion of cane sugar, called " chaptalising " in Prance, is prac- 
ticed, under certain very carefully guarded conditions, to in- 
crease the yield of alcohol, and commercial glucose is used in 
the same way. In Germ any the addition of sugar to " musts " 
deficient in this material, is permitted. A cheap wine is 
sometimes put upon the market which contains no juice of 
the grape whatever, but is made from cider as a basis, to 
which is added alcohol, tannin, glycerin, glucose, cream of 
tartar, orris root, ethereal oils, and frequently cenanthic 
ether. An extract is frequently made from raisins, which 
is colored and flavored to imitate wine. 



278 SANITARY AND APPLIED CHEMISTRY 

Wine is subject to numerous diseases, such as souring, 
ropiness, bitterness, and molding. Poor wines or those 
that have deteriorated are sometimes distilled to make 
brandy. 

Experiment 144. Test a small portion of wine in a test 
tube for grape sugar, by the Fehling test. 

Experiment 145. Evaporate 10 cc. of wine to one half 
its volume on a water bath, and to the solution add 50 cc. 
of a mixture of alcohol and ether. Put this solution in a 
flask and allow to stand tightly corked for some time, and 
notice the acid potassium tartrate which crystallizes out. 

Experiment 146. Acidify a sample of wine with hydro- 
chloric acid, heat to boiling, and add a few drops of barium 
chlorid. If there is more than a trace of barium sulfate, 
" plastering " of the wine is indicated. Normal wine does 
not contain over .06 % of sulfuric acid calculated as potas- 
sium sulfate. 

CIDER 

The fresh juice of the apple, known as sweet cider, is a 
very convenient solution for growth of the yeast Saccha- 
romyces apiculatus, which starts fermentation, and so cider 
does not long remain sweet. The crushed apples are pressed 
in a cider press, and the juice is then run off into barrels 
and allowed to ferment. The refuse left after the juice has 
been expressed is called " pomace," and is utilized in some 
other industries. (See p. 219.) In some countries more care 
is used in the preparation of this beverage, and it is clarified 
by the use of gelatin and racked off or filtered from the de- 
posited matter. This process tends to improve the quality 
of the cider. 

Cider contains from 3 to l°f of alcohol by volume, besides 
malic acid, sugar, extractives, and mineral salts. 



ALCOHOLIC BEVEEAGES 279 

ADULTERATION AND FALSIFICATION OF CIDER 

There are found on the market samples of cider made by- 
adding water to the pomace, and repressing ; but this cider 
is more frequently used as a basis for the manufacture of 
other beverages. The most important sophistications of 
cider are water, sugar, and especially the use of preserva- 
tives. The preservatives most commonly used are benzoic 
acid, salicylic acid, sulfurous acid or sodium sulfite, and 
betanaphthol. Mustard seeds, borax, and horse radish are 
also used. From some experiments by the author 1 it was 
shown that the effect of those substances is to retard the 
fermentation, and not to ultimately prevent it. It is prob- 
ably true that substances that will retard fermentation will 
also have a tendency to produce indigestion. 2 (See Chapter 
XXV.) Substances which have a proper place when used as 
medicines should not be taken in small doses with the food 
from day to day. 3 

Perry, or pear cider, is made and consumed more exten- 
sively abroad than in the United States. It does not differ 
essentially except in flavor from cider. 

Experiment 147. To test for salicylic acid in cider or 
beer, acidulate a sample with sulfuric acid and shake with 
a mixture of equal parts of ether and petroleum naphtha. 
Eemove the ethereal layer with a pipette and allow to evapo- 
rate to small volume on a watch glass. Add a little water 
and a few drops of ferric chlorid solution, when the pres- 
ence of salicylic acid will be indicated by a violet color. 

1 Kas. Univ. Quar., VI, A, p. 111. 

2 Shepard, Report, Ohio Food Commis., 1904. 
8 Harrington, " Practical Hygiene," p. 211. 



280 SANITARY AND APPLIED CHEMISTRY 

• BEER 

This beverage is a representative of malt liquors. Accord- 
ing to the best authorities, genuine beer should be made 
from malt, starchy material, hops, yeast, and water, and noth- 
ing else. Malt is made by soaking barley in water for 
several days, then piling it up on the flpor or " couching " 
till it sprouts and the little radical starts to grow ; then 
the process of germination is retarded by " flooring," as it is 
called ; i.e. spreading in progressively thinner and thinner 
layers upon the floor, and germination is finally stopped by 
drying the grain. The color of the malt depends upon the 
temperature at which this drying is conducted. If dried be- 
tween 32° and 37° C, it forms a "pale malt"; if from 38° 
to 50°, a brown malt. In the process of malting the albu- 
minous substances of the grain are changed in part to diastase, 
an active ferment, which has the peculiar property of chang- 
ing starch to dextrin and then to sugar (maltose). One part 
of diastase under favorable conditions will convert 2000 parts 
of starch to sugar. 

The next process is known as " mashing. " This consists 
in grinding the malt and soaking it in water at a tempera- 
ture of 75° C. The change from starch to sugar is still more 
completely effected here. The clear infusion, called the 
" wort," is boiled with hops, and the solution is cooled very 
rapidly to 18° C. Yeast is added, in the proportion of about 
1 gal. to 100 gal. of wort, and the liquid is allowed to fer- 
ment about 8 days. It is then drawn off into settling tanks 
and finally into casks, and stored in a cool place to ripen. 
The yeast changes the sugar into alcohol and carbon dioxid, 
in accordance with the reaction, — 

C 6 H u O e = 2 C0 2 + 2 C 2 H 5 OH. 

The sugar is not completely eliminated, as that would inter- 
fere with the agreeable taste. 



ALCOHOLIC BEVERAGES 



281 



The following analyses of malt liquors, taken from various 
sources, will give an idea of their composition : — 





6m 
H 

< 

& 




2 2 


o 

< 


pi S3 

< 2 


to H 

OP 


38 


a 

< 


Milwaukee lager, bottled . . 
H. export 


1.0100 
1.0178 


85.85 
91.11 
90.08 
89.01 
87.87 
91.63 

88.49 
89.42 


4.28 
4.40 
6.24 
3.29 
4.60 
3.36 
3.93 
4.40 
4.69 
2.73 
6.78 
4.70 
4.74 
5.44 


4.18 
6.15 
3.46 
4.22 
9.40 
5.34 
5.79 
6.38 
7.21 
5.43 
9.52 
6.59 
5.65 
5.42 


1.10 

2.14 

.59 

.69 

.95 
.88 
1.20 
1.81 
1.62 
5.35 
2.62 
1.07 
1.62 


1.57 

2.54 

.90 

2.65 

3.11 
3.73 
3.47 
3.97 
2.42 
2.09 
3.08 
1.81 
2.60 


.06 
.07 
.23 

.16 
.15 
.16 
.17 
.89 
.25 
.28 
.28 
.17 


.20 
.31 


Philadelphia ale, bottled . . . 
Pilsen lager 


1.0059 
1.0114 


.40 


Schenk 


.20 


Lager ( beer ) 

Export beer 


1.0162 
1.0176 
1.0213 


.23 
.25 
.26 




1.0137 


.15 


Dublin stout, XXX .... 
Porter 


1.0191 


.36 


Ale 


1.0141 


.31 


Burton bitter ale 







The quality of the beer depends upon the manner of 
brewing, the temperature, qualities of ingredients, method 
of storing, kind of water used, quality of the yeast, whether 
"top yeast" or "bottom yeast," and the temperature at 
which it is stored. The lager beer proper, or store beer, 
should be kept in a cool place for several months before 
being used. Very much of the beer in use in the United 
States is what is known as "present use" beer. Bock beer 
is a strong variety of beer made for use in the spring only, 
and Weiss beer is a very weak beverage used in Germany. 
Ale, porter, and stout are richer in alcohol than lager beer. 

In the manufacture of beer the tendency is to use as little 
of expensive ingredients as possible, so in cheap beers, part, 
or all, of the barley malt is replaced by some other grain, as 
corn or rye, and even a special kind of glucose is added to 



282 SANITARY AND APPLIED CHEMISTRY 

furnish a material that will readily ferment. It is asserted 
that sometimes the bitter principle in cheap beer is also 
replaced by quassia and other bitter substances. Most of 
the beer on the market contains from 2 to 4 % of alcohol 
by weight. There are comparatively few adulterations in 
beer except those mentioned. Salicylic acid is, however, 
frequently used as a preservative. A kind of so-called beer 
has been put upon the market in some prohibition localities. 
This often contains less than 2% of alcohol, and is sold 
under a variety of special names. 

Sake, the favorite beverage of the Japanese, is prepared 
from rice fermented by the use of a peculiar fungus grown 
for that purpose. It contains about 12.5 °J of alcohol. 1 

Experiment 148. To show the presence of alcohol in a 
sample of wine, beer, or cider, heat about 100 cc. in a 500 cc. 
flask, into the neck of which is fitted the large end of a cal- 
cium chlorid tube. As soon as the liquid begins to boil 
slowly, light the vapor that escapes at the top, and observe 
that it burns with a characteristic alcohol flame. 

Experiment 149. Collect some of the distillate from a 
sample of malt or fermented liquor, by boiling it very 
gently in a 500 cc. flask, to which is fitted, by a perforated 
cork, a glass tube about 60 cm. long, bent at an acute angle 
above the cork. At the other end of the glass tube place 
a small flask or test tube surrounded by cold water. The 
alcohol will condense in the cooled flask. 

Experiment 150. Test some of the alcohol, first by taste, 
second, by burning, third, by adding to a sample about 1 g. 
solid NaOH and a few crystals of iodine. The formation 
of a yellowish crystalline precipitate of iodoform, CHI 3 , 
which has a characteristic odor, indicates the presence of 
alcohol in the distillate. 

1 Church, "Food," p. 195. 



ALCOHOLIC BEVERAGES 283 



DISTILLED LIQUORS 

Distilled liquors, such, as rum, gin, brandy, and whisky, 
are made from some saccharine substance like molasses, or 
some starchy substance like corn, rye, barley, or rice. The 
chemical action in the case of starch is first to change the 
starch by the addition of ground malt to sugar, which is then 
decomposed in the process of fermentation with yeast, into 
alcohol and carbon dioxid. Diastase, which is present in the 
malt, is the active agent in transforming the starch to sugar. 
This sugar is principally maltose, mixed with one of the 
dextrins. 1 After fermentation the alcohol is distilled off, 
and with it some other volatile substance, especially ethers, 
which give the characteristic odor and taste to the liquor. 
(See also Bread, p. 160.) 

Originally the liquid actually distilled over was used 
directly as a beverage. This was about of proof strength, 
and had the characteristic flavor of the substance from 
which it was distilled. Practically, at the present time, a 
large proportion of the liquor on the market is made by 
the rectifiers, using as a basis pure alcohol and "high 
wines," which are diluted, colored, and flavored to imitate 
the required beverage. 

The method used in making alcohol is to prepare what is 
called the mash by crushing the grain and other starchy 
material into a fine pulp, and soaking it with water, cooling 
it quickly, and allowing it to ferment with yeast. Some- 
times the mash is made by the use of sulfuric acid, thus 
converting the starch directly into dextrin. The mash, after 
fermentation, is distilled in an apparatus so arranged that 
the alcohol, as it is volatilized, shall be quickly cooled and 
condensed in a coiled pipe. Theoretically, — 

1 Jago, "The Science and Art of Bread Making," p. 126. 



284 SANITARY AND APPLIED CHEMISTRY 

100 parts of starch, yield 56.78 parts of alcohol, 
100 parts of cane sugar yield 53.08 parts of alcohol, 
100 parts of dextrin yield 51.01 parts of alcohol, 
but practically this output is not reached. 

The last part of the distillate usually contains more of the 
higher alcohols of the series, especially amyl alcohol, which 
is one of the constituents of " fusel oil." This is considered 
one of the most injurious ingredients in ordinary liquors. 

Brandy should be made by the distillation of wine, and 
should obtain its odor and flavor from the fermented juice 
of the grape. Practically in the hands of the rectifier, it 
can be made from alcohol diluted, colored with caramel, 
flavored with oil of cognac, which is distilled from the marc 
or refuse, from the manufacture of wine. The flavor of 
brandy is much improved by age, but many processes of 
artificial aging have been devised. 

Whisky, as originally made from corn, barley, or 
potatoes, had a brownish color, and a peaty or smoky flavor 
that was imparted to it by the smoke of the peat fires 
used in its manufacture in Scotland and Ireland. This 
flavor is now imparted to the commercial article by the use 
of creosote or some similar compound. 

Eum was originally made in the West Indies from 
residue left after the manufacture of cane sugar or from 
molasses, and the peculiar flavor it possessed was produced 
by the volatile oils that are developed in the manufacture 
of sugar from cane juice. Much of it is now manufactured 
by the " rectifier " in a manner already described. 

Gin was originally made by the distillation of an alcoholic 
liquid with juniper berries, but at present the rectifier adds 
to the diluted alcohol, oil of juniper or turpentine, or both, 
some aromatic seeds and fruits, and redistills the mixture. 
Many roots and drugs are frequently added to improve the 
flavor of gin. 



ALCOHOLIC BEVERAGES 285 

Experiment 151. Alcohol may be made from the fer- 
mentation of a saccharine liquid, as follows: In a 2-liter 
flask mix 60 cc. of molasses with 700 cc. of water, and add a 
small amount of yeast, and set aside in a warm place for 
a day or two. When the mass foams and carbon dioxid is 
freely given off, distill slowly by attaching a condenser, or 
a cork, through which passes a long tube bent to an acute 
angle, as in Experiment 149. Examine the distillate by 
taste and smell, and by the test mentioned in Experi- 
ment 150. 

Dr. Battershall l says : " The most prevalent form of 
sophistication with brandy, rum, and gin is the artificial imi- 
tations, and the direct addition of substances injurious to 
health is of unfrequent occurrence. " He believes that the 
most dangerous ingredient in the fictitious product is the 
fusel oil, which is a mixture of the higher alcohols, but 
other authorities have made experiments with this substance, 
and find no injurious effect, even when considerable quanti- 
ties mixed with whisky are taken for quite a length of time. 
It is suggested that perhaps the compounds which make 
some spirits, especially those which are recently distilled, or 
" raw, " more injurious than those which are " aged," may be 
other by-products of fermentation, such as furfurol. 

LIQUEURS OR CORDIALS 

These beverages consist of very strong alcohol, flavored 
with aromatic substances, and often highly colored, with a 
coal tar or a vegetable coloring matter. Absinthe, the most 
important of these, is yellowish green in color, and contains 
oil of wormwood, a substance that has a very injurious 
effect on the nervous system, with anise, sweet flag, cloves, 
angelica, and peppermint. This liquor usually contains over 
50% of alcohol. 

1 " Food Adulteration and its Detection, " p. 192. 



286 SANITARY AND APPLIED CHEMISTRY 

Other beverages of this class are maraschino, distilled 
originally from the sour Italian cherry; chartreuse and 
benedictine, named from the monasteries where they were 
originally made ; kumme] ; curagoa, made from the rind of 
bitter oranges ; ratafia, made in France from fruits ; angus- 
tura and vermuth. Nearly all these contain a large amount 
of sugar and a high per cent of alcohol, and are flavored with 
various essential oils, herbs, and spices. 

PHYSIOLOGICAL ACTION OP ALCOHOL 

The question as to whether alcohol is, properly speaking, 
a food, or whether it simply acts as a stimulating beverage, 
is one that has occasioned a vast amount of discussion. 
The best authorities seem to agree that there are cases 
of disease in which it is the most useful material that can 
be administered. Professor Atwater, who has investigated 
the action of alcohol in his respiration calorimeter, speak- 
ign of its use in disease says : " What is wanted is a 
material which will not have to be digested and can be 
easily absorbed, is readily oxidized, and will supply the req- 
uisite energy. I know of no other material which would 
seem to meet these requirements so naturally and so fully 
as alcohol. It does not require digestion, is absorbed by 
the stomach and presumably by the intestines, with great 
ease. Outside the body it is oxidized very readily, within 
the body it appears to be quickly burned, and it supplies a 
large amount of energy." From one fifth to one seventh 
of the total calories of the diet may be replaced by alcohol. 

The same author says of the results of his experiments, 
that he found that " the alcohol was almost completely 
oxidized. The kinetic energy resulting from that oxida- 
tion agrees very closely with the potential energy of the 
same amount of alcohol as measured by its heat of combus- 
tion as determined by the bomb calorimeter, and the alco- 



ALCOHOLIC BEVERAGES 287 

hoi served to protect body protein and fat from oxidation." 
Alcohol is inferior to carbohydrates, however, to protect pro- 
tein of the body from oxidation. 1 As a stimulant, alcohol 
acts primarily upon the nervous system and the circulation, 
and quickens the transmission and enhances the effect of 
nerve currents. Although alcohol tends to remove muscu- 
lar fatigue and to increase the force of muscular action, 
yet its use is absolutely forbidden to athletes in training, 
and soldiers in the army continue in better health if they 
entirely abstain from the use of this substance. 

It will be seen that although alcohol has some right to be 
regarded as food, yet it is not a food of any practical im- 
portance, for it can merely replace a certain amount of the 
fat, and perhaps of the carbohydrates, in the body, while its 
secondary effects on the nervous and vascular systems coun- 
teract, to a large extent, the benefits derived from the pro- 
duction of heat and energy by its oxidation. 2 

1 Thompson, " Practical Dietetics," p. 229. 

2 Hutchison, " Food and Dietetics." 



CHAPTER XXIV 
FOOD ACCESSORIES 

A large number of aromatic substances, which have no 
direct food value are prized for the agreeable flavor which 
they impart to food. Condiments are by some writers de- 
fined as the substances eaten with meat and used with salt, 
while the term spices is restricted to those substances which 
are used with sugar. It is however impossible to draw a 
definite line between the two classes of substances. 

The spices, since they are used only in small quantities 
and are quite expensive, readily lend themselves to all kinds 
of falsification and adulteration. 

The adulterants are usually of a harmless character, 
and consist of English walnut shells, Brazil nut shells, 
almond shells, cocoanut shells, date stones, sawdust, linseed 
meal, cocoa shells, red sandalwood, Egyptian corn, rice flour, 
ground crackers, or " hard tack," bran and many other by- 
products from milling, plaster, corn meal, turmeric, cotton- 
seed meal, olive stones, and pea meal. 1 Various mixtures 
of some of the above are prepared and colored to imitate 
each of the ground spices and put on the market, at a very 
low price, for use in spice mills. In most cases these fraudu- 
lent mixtures can be detected only by the skilled chemist 
or microscopist, so the only safeguard of the housekeeper 
is to buy of reliable dealers, get the goods in sealed pack- 
ages, and to pay a fair price. In most cases it is safer to 
buy the unground spice. A brief account only of the source 
and properties of the most important products will be given. 

1 Rep. Conn. Agric. Exp. Station, 1893-1904. 
288 



FOOD ACCESSORIES 289 

Cloves are the dried flower buds of a plant belonging to 
the Myrtle family, growing in Ceylon, Brazil, India, the East 
Indies, and Zanzibar. The tree, which is an evergreen, is 
usually less than 40 ft. high. After the buds are picked 
they are laid in the sun to dry. The volatile oil of cloves, 
which may be distilled off with water, contains about 70% 
of eugenol, C 10 H 12 O 2 . In addition to the use of the clove 
" stock " above mentioned, " exhausted " cloves, both whole 
and powdered, — that is, those which have been deprived of 
a portion of their volatile oil, — are put upon the market 
and mixed with fresh cloves, so that the fraud shall be less 
apparent. 

Experiment 152. Grind about 15 grams of cloves in a 
porcelain mortar and introduce into a liter retort with 
water and boil for some time, condensing the steam in a 
flask floating in a pan of water. Pour the distillate into a 
tall tube and allow it to stand, and the oil of cloves will rise 
to the surface. 

Cinnamon is the inner bark of a tree of the Laurel 
family, which is cultivated in Ceylon, Java, Sumatra, and 
surrounding countries. A cheaper and more common cassia 
which is also commercially known as cinnamon, comes from 
another tree of the Laurel family, which grows in China 
and India. Cassia buds, the dried flower of the China cas- 
sia, are also upon the market. The odor of cinnamon is 
due to the presence of a volatile oil, which consists princi- 
pally of cinnamic aldehyde, C 6 H 5 CH : CH.CHO. A " stock " 
colored with red sandalwood is commonly used as an adul- 
terant; this stock frequently consists largely of foreign 
barks, such as that of the elm. 

Pepper is the dried berry of the Piper nigrum, a climbing 
plant which grows in tropical countries. For preparing 
black pepper the unripe fruit is dried in the sun, but to pre- 
pare the white pepper the ripe fruit is soaked in water and 



290 SANITARY AND APPLIED CHEMISTRY 

the skins are removed by friction. The taste and odor 
of pepper is due to the presence of an essential oil, a hydro- 
carbon, having the formula C 10 H 18 , and another important 
substance called piperin, C 17 H 19 lSr03. In addition to the or- 
dinary adulterants in ground pepper, Egyptian corn and 
" long pepper " are used, while cayenne pepper is often added 
to raise the pungency nearer to that of the pure product. 

Ginger is the rhizome of the Zingiber officinale, an 
annual herb which is a native of India and China, and is 
cultivated in the West Indies, Africa, and Australia. Black 
ginger is prepared by scalding the freshly dug root, and 
drying immediately. White, or " scraped," ginger is the 
same material that has been scraped and sometimes further 
whitened by treatment with some bleaching agent. Pre- 
served ginger is prepared by boiling the root and curing 
with sugar. A volatile oil and a pungent resin give to gin- 
ger its characteristic odor and taste. Ginger is often adul- 
terated by mixing with it ginger roots that have been ex- 
hausted with alcohol. The alcoholic extract or water extract 
is used for the manufacture of ginger ale. 

Nutmeg and mace occur in the fruit of trees of the Myris- 
tica family, which grow especially in the Malay Peninsula. 
The tree grows from 20 to 30 ft. high, and produces flowers 
after about the eighth year. The fruit is surrounded by a 
fleshy crimson covering, which when dried furnishes the 
mace of commerce, and the hard seed the nutmeg. This is 
further prepared by washing with milk of lime. Nutmegs 
contain from 3 to 5% of a volatile oil. As the whole nut- 
meg is used by the cook, rather than a ground product, 
there is not much opportunity for adulteration. Mace has 
the usual adulterants, and frequently a wild mace, known as 
Bombay mace, which is practically without taste is added. 

White mustard is the seed of the Sinapis alba, and black 
mustard that of the Sinapis nigra. The plant, which is 



FOOD ACCESSOEIES 291 

an herb, having yellow flowers, grows both in the United 
States and in Europe. Both varieties contain about 35% of 
a fixed oil, which can be separated by heat and pressure, a 
soluble ferment called myrosin, and sulfocyanate of sina- 
pin, C 16 H23N"0 5 . The black mustard contains potassium my- 
ronate, which, when moistened with water, forms the volatile 
oil of black mustard, known to the chemist as allyl isothyocy- 
anate, C 3 H 5 CSN. This has a strong mustard-like odor, and 
the vapor excites tears. This oil produces blisters on the skin, 
and hence the use of the so-called " mustard plaster/' The 
chief adulterants of ground mustard are wheat, flour, or 
starch, mustard hulls, and turmeric to restore the yellow 
color lost by the adulteration with a starch powder. Some- 
times cayenne pepper is also added to restore the pungency. 

VINEGAR 

Since most of the vinegar of commerce is used in connection 
with spices and in the preparation of pickles, etc., its prop- 
erties may be studied in this connection. Vinegar is dilute 
acetic acid, C 2 H 4 2 , flavored with the fruit ethers, and can 
be made from any dilute alcoholic liquor. The whole pro- 
cess of the conversion of cane sugar to vinegar would be rep- 
resented by the equations, — 

CiiHaOu + H 2 = 2 C 6 H 12 6 ; 

Cane sugar Invert sugar 

C 6 H 12 6 = 2C 2 H 5 OH + 2C0 2 ; 

Alcohol 

C 2 H 5 OH + = C 2 H 4 + H 2 ; 

Aldehyde 

c 2 h 4 o + o = c 2 h 4 o 2 . 

Acetic acid 



292 SANITARY AND APPLIED CHEMISTRY 

The change from alcohol to vinegar is brought about by 
the ferment mycoderma aceti, found in the " mother." The 
conditions for this fermentation are an alcoholic liquid con- 
taining not over 12% of alcohol, an abundance of air, a tem- 
perature of from 20° to 35° C, and the presence of the ferment. 

The materials used are (1) wine ; (2) other fermented fruit 
juices; (3) spirits like diluted whisky, or residues from 
the manufacture of sugar; (4) malt wort, or beer; (5) 
sugar beets. There are several processes used for the manu- 
facture of vinegar on a large scale, in addition to the usual 
process of allowing the cider to ferment in an ordinary 
barrel in a warm cellar with the bunghole left open for two 
or three years. 

In France and Germany vinegar is made from wine by 
pouring it from time to time into an oaken vessel which has 
been soaked with boiling vinegar, and then siphoning off into 
storage tanks. The " mother casks " are used for a long time, 
till they contain a large amount of argols, ferment, etc. 

Another method is by the " quick vinegar process, " which 
was introduced by Schutzenbach in 1823, and is quite exten- 
sively used for spirit vinegar in Germany and the United 
States, and for malt vinegar in England. 

In this process, an upright cask about 10 ft. high, and 
provided with a perforated false bottom about a foot above 
the true bottom, is filled with beech or oak shavings. Just 
under the false bottom a series of holes slanting downward 
is bored entirely around the cask. The shavings are soaked 
in warm vinegar, and covered by a wooden disk perforated 
with numerous holes, through which cords are loosely drawn. 
There are also several glass tubes extending through this 
disk to assist in the circulation of the air. After covering 
the cask with a wooden cover having a hole in the center, 
the dilute alcoholic liquor is poured into the upper compart- 
ment and slowly trickles over the shavings, 



FOOD ACCESSORIES 293 

As the process of oxidation proceeds, considerable heat is 
developed, and this causes an upward current of air which 
enters the cask below the false bottom, and escapes to the 
upper part through the glass tubes. By a siphon the par- 
tially acetified liquid is drawn off into a second cask. With 4 % 
of alcohol in the original liquid, good vinegar will be drawn 
from the second vat. If " vinegar eels " appear, the convert- 
ing cask is treated with vinegar so hot that when drawn out 
it has a temperature of 50° C, which kills the eels. When 
spirit is used in this process, a little infusion of malt is added 
to furnish organic matter sufficient for the growth of the 
ferment. 

Wine vinegar may be red or yellowish in color, and con- 
tains from 6 to 9% of absolute acetic acid. Beer and malt 
vinegars are higher in specific gravity than wine vinegar, and 
contain considerable extractive matter, and from 3 to 6 % of 
acetic acid. Cider vinegar has the odor of apples, and when 
evaporated yields an extract that smells and tastes like baked 
apples. It contains malic acid and from 3^- to 6% of acetic 
acid. The acidity should never be below 3 % and the spe- 
cific gravity should never be less than 1.015. 

Imitation vinegars are sometimes made by the use of acetic 
acid distilled from wood, or from some mineral acid, and 
flavored with acetic ether and colored with caramel. The 
extract from this imitation vinegar differs from malt 
vinegar in not containing phosphate, and from wine vinegar 
in the absence of tartaric acid, and from cider vinegar in the 
absence of malic acid. 

The acidity of vinegar assists in the softening of some 
foods, such as beets, cabbage, cucumbers, hard-boiled eggs, 
corned beef, and lobsters, but it should not be used in excess 
on account of its tendency to cause anemia and emaciation. 

Experiment 153. The approximate acidity of a sample of 
vinegar may be ascertained by the use of saturated lime- 



294 SANITARY AND APPLIED CHEMISTRY 

water. This is made by allowing water to stand for some time 
with frequent shaking over slaked lime. The strength of this 
is very nearly 20 normal. To test the vinegar, 2.75 ec. are 
placed in a small Erlenmeyer flask with some water, and a 
few drops of phenolphthalein as an indicator, and titrated 
with limewater contained in a burette. When the pinkish 
color shows that the free acid has been neutralized, read the 
number of cubic centimeters of limewater used, and divide 
this by 10. This gives the percentage of acid in the vinegar. 

Experiment 154. To detect a free mineral acid in vinegar, 
add to 5 cc. of vinegar 5 or 10 cc. of water ; after mixing 
well, add 4 or 5 drops of an aqueous solution of methyl-violet 
(one part of methyl-violet 2 B in 10,000 parts of water). 
The occurrence of a blue or green color indicates a mineral 
acid. 1 

Experiment 155. Caramel is often used to color imitation 
vinegars. To detect this, place about 25 cc. of the sample in 
a large test tube or in a bottle, and add to it about 10 grams 
of fullers' earth, shake the sample vigorously for several 
minutes, and filter. The first portion of the liquid which 
passes through the filter should be filtered again. Eeturn 
the filtered sample to original tube, and compare the color 
of this solution in a similar tube with that of an equal 
quantity of vinegar that has not been treated. If the treated 
sample is considerably lighter in color than that which has 
not been treated, the vinegar is probably colored with cara- 
mel. Caramel occurs naturally in malt vinegar. 2 

Experiment 156. To obtain the acid, except sulfuric, of 
vinegar free from extractive matter, pour 250 cc. of vinegar 
into a flask, add to it 25 cc. of dilute sulfuric acid, and 
distill by the use of the simple apparatus described in Ex- 

!Bul. 65, U. S. Dept. Agric, Bu. Chem., p. 64. 
2 Bui. 100, U. S. Dept. Agric, Bu. Chem., p. 48. 



FOOD ACCESSORIES 295 

periment 149. Collect the distillate in a flask and examine 
its odor, taste, etc. 

SALT 

Common salt, NaCl, has been used for thousands of years 
as an essential ingredient of foods, and as a preservative. 
Fortunately, it is found in numerous localities all over the 
world. In the United States, the chief salt-producing local- 
ities are Michigan, New York, Kansas, and Ohio, which to- 
gether furnish about 90 °f of the total output, 1 and smaller 
quantities are obtained from California, Utah, West Virginia, 
Louisiana, Oklahoma Territory, Texas, and Pennsylvania. 

Salt is obtained either as rock salt, which is mined in sev- 
eral localities, by the evaporation of sea water or that of salt 
lakes, or by the evaporation of brine, which is obtained from 
salt wells or borings into the salt bed. Most of the table salt 
of commerce is made by the latter process. In some localities 
solar evaporation is relied upon for concentration of the brine, 
but usually the brine is heated in an open pan by direct heat 
or in a " Grainer " by steam heat. Many producers are 
introducing cement evaporating pans, automatic self-acting 
rakers, and vacuum pans. 

The brine when pumped from the wells contains some 
impurities, and these, especially the calcium sulfate, are 
deposited when the brine is first concentrated, so that in this 
way the brine can be partially purified in the first pan, 
before it is run into the evaporating pans proper. The com- 
position of a good brand of salt is as follows : — 

Per Cent 

Sodium chlorid 97.75 

Insoluble residue .03 

Calcium sulfate 1.84 

Magnesium chlorid .38 

Total 100.00 

1 Bailey, International Congress of Applied Chemistry, Berlin, 1903. 



296 SANITARY AND APPLIED CHEMISTRY 

Most of the salts on the market contain from 97 to 99 °Jo of 
pure salt. When salt absorbs moisture it becomes hard and 
inconvenient for domestic use. This is sometimes remedied 
by the addition of a small quantity of starch or some such 
material. 



CHAPTER XXV 
PRESERVATION OF FOOD 

It is only within the last hundred years that any adequate 
methods for the preservation of food have been devised ; in 
fact, within the last fifty years the greatest advances have 
been made in this art. Formerly, fruits, vegetables, and 
meats must be consumed in the locality where they were 
produced, and fruits especially must be used as soon as ripe. 
In 1804 M. Appert of Paris found that meat and other 
organic substances would keep indefinitely if sealed and then 
heated in boiling water. In 1810 he suggested the method 
of introducing steam and heating, and then sealing, so that 
when the vessel cooled a vacuum was formed. 

Canned meats and fruits have been kept for quite a number 
of years, and were found to be in good condition. By the 
use of modern methods of preservation the season for the use 
of each fruit has been extended; and the product of one 
climate can be transported to another climate for consump- 
tion. Meats and vegetables can be preserved for months, and 
so the variety of food for man has been greatly increased. 
Since the fermentative changes that take place when food 
is kept for some time are due to the growth of various micro- 
organisms, any process which will prevent this growth or 
keep these organisms out of the food will assist in its pres- 
ervation. Warmth, moisture, and access of germ-laden air 
are conditions favorable for the decomposition of food. 

Some of the methods adopted for the preservation of food 
are : (1) maintaining a low temperature ; (2) drying so as to 

297 



298 SANITARY AND APPLIED CHEMISTRY 

remove as much moisture as possible ; (3) addition of sugar 
or glucose; (4) the use of saltpeter or brine; (5) pickling with 
vinegar ; (6) canning or placing in a sterilized atmosphere ; 
(7) the use of chemical preservatives. 

Fermentation and decay take place best at a moderately- 
high temperature, so cold storage is introduced not only to 
transport fruits and meats from one section of the country 
to another, but also to keep the food from the season when it 
is abundant until the season when it is scarce. Preservation 
by the use of salt, smoke, sugar, saltpeter, or vinegar fur- 
nish conditions unfavorable to the growth of microorgan- 
isms, and so decay is prevented. Dried or "jerked" meat 
will keep a long time for the same reason, especially in a 
dry climate. 

In smoking the meat, which is usually previously salted, 
it is dried and penetrated by acetic acid, creosote, and other 
preservatives of the smoke. 

In "quick smoking" processes the meat is dipped several 
times in a solution of pyroligneous acid (which is made 
by the distillation of wood) and dried in the air. Other 
chemicals are frequently used. 

The process of food preservation by canning or protecting 
from air and sterilizing has developed to an enormous extent 
in the United States. When we consider the annual output 
of 100,000,000 cans of corn, 1 the same quantity of peas, and 
150,000,000 cans of tomatoes, besides millions of cans of 
other vegetables and fruits, some idea of the value of this 
process to the human race is obtained. 

Fortunately, too, most of this food is prepared in such a 
way as not to be injurious to the system. The object to be 
attained in canning is to destroy the microorganisms of 
various kinds, so it makes no special difference whether a 
little air remains in the can or not, as long as the contents is 
1 Leach, " Food Inspection and Analysis, " p. 689. 



PRESERVATION OF FOOD 299 

perfectly sterilized, although formerly it was held that all 
the air must be excluded. 

In domestic practice, fruit may be preserved by packing 
in glass cans, filling nearly full of water, adding some sugar 
if desired, and then immersing the cans nearly to the neck 
in a vessel of cold water. The water is heated to boiling, 
and allowed to boil from 15 to 30 m., dependent on the size 
of the fruit, and then the cans are removed from the water 
and immediately sealed. This process has the advantage of 
preserving the fruit whole and unbroken. 

Another method much in vogue is to cook the fruit or 
vegetables, then put it, while still hot, in glass or tin cans 
that have just been taken out of boiling water, and to seal 
immediately with the ordinary glass cover and rubber 
washer or with cork and sealing wax. 

The method used at canning factories is, in general, to 
pack the material in tin cans, with the required amount of 
water, and after sealing to cook with hot water or steam. 
The cans are then punctured to allow the excess of air to 
escape, again sealed with a drop of solder, and again heated 
for some time to destroy all microorganisms. 

A more modern method of canning is to cook the fruit at 
a temperature of 82° to 88° C. before transferring to the 
cans, and afterward heat in the cans, when sealed, to a 
temperature of about 125° C. in dry air retorts, so that it 
shall be completely sterilized. 1 This process can be fin- 
ished in a shorter time than the former, and on account of 
the higher temperature employed is very effective. 

Experiment 157. To show the effect of exclusion of ordi- 
nary air from fruit, prepare two samples thus : Place some 
hot apple sauce in two 250 cc. bottles that have just been 
heated with boiling water. In the mouth of one bottle 

1 Ibid. p. 690. 



300 SANITARY AND APPLIED CHEMISTRY 

place a perforated cork, through the opening of which 
passes a calcium chlorid tube packed with cotton, that has 
been heated in an oven to 120°C. In the mouth of the other 
bottle place a cork having a small opening in it. Allow 
these bottles to stand for a week or more in a warm place, 
and notice the almost entire absence of mold in the bottle 
which is protected from the microorganisms of the air by 
the cotton, and the abundant mold on the surface of the 
sauce in the other bottle. 

When canned food spoils if put up in tin cans, the 
can usually becomes convex on the ends, instead of con- 
cave, as it is found normally, on account of the genera- 
tion of gases by fermentation. It is not an uncommon 
practice for manufacturers to puncture these " swells " and 
reheat them to stop fermentation, and afterward solder 
them again, and put them on the market. 

Since tin cans are used in the preservation of food, and 
as the tin plate, as it is called, from which the cans are 
made, often contains considerable lead, it is not uncommon 
to find salts of tin, iron, and lead in the canned products. 
This is partly due to carelessness in soldering of the cans, 
and allowing the drops of the solder, which may contain 
50% of lead, to remain inside the can, and partly because 
the acid fruits act on the tin plate of which the can is com- 
posed. 

Formerly very grave danger was apprehended from the 
metals that might be contained in canned goods, but 
the fact is that we have not experimentally proven whether 
the small quantities that are found have a poisonous effect 
or not. 

Experiment 158. To show the presence of iron in canned 
fruit, test some of the juice from a can of California grapes 
(better one that has been canned for some time) with a 
little of a strong infusion of tea. Since the tea contains 



PRESERVATION OP FOOD 301 

tannic acid (Experiment 141) it will form a black coloration 
(ink) with the iron that has been dissolved from the tin 
plate by the acid of the fruit. 

CHEMICAL PRESERVATIVES 

In recent years the practice of adding preservatives to 
food has greatly increased. These preserve the foods by 
preventing the growth of bacteria. There may be a differ- 
ence of opinion in regard to the use of some of them, but it 
seems perfectly reasonable that antiseptic substances which 
will prevent the decay of food will be liable also to retard the 
disgestive processes. Food that has really begun to decay 
may, by the use of these preservatives, be put on the market 
and sold as wholesome. It is no defense of the practice to 
claim that food that has been thus treated is better than if 
it had not been treated, for such food, which has begun to 
decay or ferment, should be condemned without question. 

When preservatives are added to food intended for the 
use of invalids and young children, they are especially 
liable to interfere with the digestion and prove injurious 
to the system. Many tests have been made upon the 
lower animals, and some results have been obtained which 
indicate that some preservatives may be used with impu- 
nity, but the time has not come to admit the use of preserv- 
atives in foods without question. This position has been 
taken by the health authorities in many states ; and where 
the use of these substances is not actually prohibited, they 
require at least that each package so preserved shall be 
labeled to that effect. ; 

In a recent article * Dr. Vaughan says, " A true food 
preservative must keep the substance to which it is added 
in a wholesome condition so that it can be consumed by 
persons in every physical condition of life without impair- 

1 Jour. Am. Med. Assoc, Vol. XLIV., p. 753. 



302 SANITARY AND APPLIED CHEMISTRY 

roent of health, or danger of life. It is not the function of a 
food preservative to impart to the food a deceptive appear- 
ance and to make it look better than it actually is. The law 
. . . forbids the use of all meat preservatives that restore 
the color and fresh appearance to partially decomposed 
meats. ... To prevent the development of those bacteria 
that produce odoriferous substances while the more toxic 
bacteria, that develop no telltale odor, continue to grow and 
multiply, does not comply with the requirements demanded 
by a food preservative that asks for legal sanction. ... To 
retard the multiplication of the lactic acid bacillus, and thus 
prevent the souring of milk, while colon bacilli continue to 
multiply uninterruptedly is not the function of a true food 
preservative. . . . The man who adds formaldehyde to his 
milk takes down the danger signal, but does not remove the 
danger." 

In regard to the action of preservatives on the digestive 
fluids, it should not be forgotten that preservatives if 
permitted in the food are liable to be taken by persons with 
every degree of digestive impairment. The free hydrochloric 
acid of the gastric juice will be neutralized by sodium sulfite, 
if this salt is used as a preservative, and this cannot fail to 
interfere seriously with the action of the digestive enzymes. 
It seems to be well established that formaldehyde also inter- 
feres with their action. In regard to some of the other 
preservatives, sufficient experiments have not been made to 
prove definitely that they interfere with the digestive func- 
tions. 

The author above quoted believes that a food preservative 
in order to receive legal sanction should keep the food in a 
wholesome condition and not simply retain this appearance 
while bacterial changes continue; in the largest quantities 
used it should not impair any of the digestive processes ; 
and finally this substance must not be a cell poison, or if it 



PRESERVATION OF FOOD 303 

is a cell poison, it must be added to foods only by persons 
who have special training, and not by a manufacturer who 
has no knowledge of the subject. Foods containing these 
preservative substances should also be plainly marked, so 
that the presence of the preservative can be known to each 
consumer. 

"If the use of any preservatives is to be permitted in 
food, boric acid and sodium benzoate are the least objec- 
tionable, since they appear to have less tendency to dis- 
turb the digestive functions than have the others." x 

At the conclusion of an exhaustive series of experiments 
upon the effect of boric acid and borax on the general health, 
Dr. H. W. Wiley says : " It appears, therefore, that both 
boric acid and borax when continuously given in small doses 
for a long period, or when given in large quantities for a 
short period, create disturbance of appetite, of digestion, 
and of health." 2 

Some of the preservatives most used are borax (Na 2 B 4 7 , 
10 H 2 0), boric acid (H 3 B0 3 ), salicylic acid (HC 7 H 5 3 ), 
ammonium fluorid (NH 4 F), benzoic acid (HC 7 H 5 2 ), so- 
dium benzoate (TSTaC 7 H 5 2 ), formaldehyde (HCHO), sodium 
sulfite (!STa 2 S0 3 ) and sulfurous acid (H 2 S0 3 ), beta-naph- 
thol (C 10 H 7 OH), abrastol Ca(C 10 H 6 SO 3 OH) 2 and saccharin 
(C 6 H 4 COS0 2 ]SrH). The detection of small quantities of 
these substances in food usually requires the service of an 
experienced analyst. 

Borax and boric acid are often sold under various names, 
such as " Preservaline," and mixtures of borax with other 
preservatives are also on the market under various trade 
names. This preservative is used especially in milk and 
meat products. The method of detection given under Milk, 
Experiment 136, should be followed. 

!H. Leffman, Jour. Franklin Inst. 147 (2), 97-109. 
2 Circ. 15 or Bui. 84, U. S. Dept. Agric, Bu. Chem. 



304 SANITARY AND APPLIED CHEMISTRY 

Salicylic acid is a white crystalline powder, very soluble 
in alcohol, and soluble in 500 parts of water. It is used 
in preserving fruit products, beer, cider, milk, etc. 

Experiment 159. To test for salicylic acid, to 50 cc. of 
the substance to be tested, made feebly acid with a few 
drops of sulfuric acid, add an equal bulk of a mixture of 
equal parts of ether and petroleum spirit, and shake vigor- 
ously. Allow the liquids to separate, and draw off the 
solvent, or take it out with a pipette, filter it, and allow it 
to evaporate at a gentle heat. If salicylic acid is present, 
fine silky crystals will usually be seen. Add to the residue 
left on evaporation a few drops of water and a drop of 
very dilute ferric chlorid or of ammonium ferric alum solu- 
tion, and if there is any salicylic acid, a characteristic violet 
color is produced. 

Sodium benzoate, which is more frequently used as a 
preservative than benzoic acid, is a white granular powder, 
of a slightly aromatic odor, and disagreeable taste. It is 
readily soluble in water, and the solution is used as a 
preservative, especially for catsup, mince meat, jams, and 
jellies. 

Experiment 159 a. Benzoic acid or a benzoate may be 
detected in the absence of salicylic acid by Peter's method, 1 
which depends on oxidation of the benzoic acid to salicylic 
acid by treatment with sulfuric acid and barium peroxid, 
and then applying the ferric chlorid test for salicylic acid 
noted in Experiment 159. 

Saccharin acts both as a preservative and a sweetening 
agent. It is a white crystalline powder, soluble in 1000 
parts of cold water. It is four or five hundred times as 
sweet as cane sugar. 

Sodium sulfite is a white solid readily soluble in water. 

!Bul. 65, p. 160, U. S. Dept. Agric, Bu. Chem. 



PRESERVATION OF FOOD 305 

It has the characteristic taste of the smoke of a burning 
sulfur match. 

The sulfites are used especially to preserve meat and meat 
products, and give them a "natural" red color, and for 
alcoholic beverages, cider, fruit juices, and catsup. 

Experiment 160. As the test for the detection of sulfur- 
ous acid depends on converting it into sulfuric acid, the 
following method may be used : Place 200 g. of the sus- 
pected food, which, if solid, should be ground with water 
in a mortar, in a flask, make acid with phosphoric acid, con- 
nect with a condenser, and distill slowly, till 20 cc. have 
come over. Boil this distillate in a large test tube or small 
flask with bromin water and add a few drops of barium 
chlorid. The formation of a white precipitate of barium 
sulfate indicates that a sulfite was present. 

Formaldehyde is a gas that readily dissolves in water. 
The 40% solution is usually sold under the name of "for- 
malin." The gas has a characteristic odor. It is used as a 
preservative for fish, broken eggs, meat products, milk, etc. 
The method of testing for formaldehyde is given under 
Milk, Experiment 137. 

Experiment 161. To some egg-white, in a porcelain evapo- 
rating dish, add a moderate quantity of formaldehyde. 
Place the dish over a water bath, and warm, not above 60° C. 
for some time. Notice the leathery character of the product. 

Experiment 162. Saccharin is said by some to have slightly 
preservative qualities, but it is added to food products, such 
as canned sweet corn, principally as a sweetening agent. Tor 
its detection in jelly, preserves, or canned vegetables, use 
about 20 grams of the sample. Grind this in a mortar with 
about 40 cc. of water, strain through muslin, acidify with 2 cc. 
of dilute sulfuric acid, and shake moderately with ether. 
Separate the ethereal layer and allow this to evaporate 



806 SANITARY AND APPLIED CHEMISTRY 

spontaneously in a watch glass, and take up the residue with 
water. If saccharin is present, this solution will have a sweet 
taste. To confirm this test add one or two grams of sodium 
hydroxid, place the dish in an oil bath and heat to 250° C, 
for twenty minutes. This will convert the saccharin into 
salicylic acid. After cooling and acidifying with sulfuric 
acid, extract as usual and test for salicylic acid according to 
Experiment 159. 1 

COLORING OF FOOD PRODUCTS 

This is another method of falsifying food, and making it 
appear better than it is, or of simulating wholesome foods 
with a combination of entirely foreign substances. The 
coal-tar colors, of which there is an endless variety, lend 
themselves very readily to the coloring of foods and bever- 
ages. The use of these dyestuffs is not only liable to 
lead to injury of the health of the consumer from the poi- 
sonous nature of the coloring material, but the consumer is 
deceived so that he buys the goods thinking they are of 
greater value than they actually are. There are some of 
the coal-tar or aniline colors, which are of themselves harm- 
less, but in the process of manufacture some poisonous sub- 
stance such as arsenic or mercury is used, and a little of this 
remains in the finished product, making it dangerous for 
consumption. It is true that so far as we know the coal-tar 
colors are mostly harmless, so the chief cause for objection to 
their use is on account of the fraud on the consumer. It is 
the custom with many manufacturers of confectionery to use 
only such colors as are accompanied by certificates of the 
chemist as to their purity. In some cases vegetable colors, 
such as turmeric, logwood, annatto, Brazil wood, beets, and 
saffiower are used. The only animal coloring matter in 
common use is that of the cochineal, called carmine red. 
iBuL 65, p. 51, U. S. Dept. Agric, Bu. Chem. 



PRESERVATION OF FOOD 307 

Experiment 163. Test a sample of tomato catsup for a 
coal-tar dye by the method described in Experiment 122. 

Salts of copper are sometimes used to impart an artificial 
green color to canned goods, particularly peas, beans, brus- 
sels sprouts, and pickles. An old-fashioned method for 
greening pickles was to put a copper cent in the vinegar in 
which they were boiled. The practice of coloring food 
material by the use of compounds of copper is more common 
on the Continent than in the United States. Imported goods 
frequently contain considerable copper. 1 Examinations of 
a large number of canned vegetables greened by copper, as 
bought in Massachusetts, showed them to contain from a 
trace to 2.75 g. per can, calculated as copper sulfate. The 
author has found in an ordinary pickled cucumber the equiva- 
lent of one seventh of a grain of copper sulfate. 

Experiment 164. Incinerate fruit or vegetables in a por- 
celain evaporating dish with sulfuric acid, adding a little 
nitric acid from time to time till the carbon is completely 
consumed. Add a few drops of hydrochloric acid to the 
ash, filter into a small test tube, and add to this solution an 
excess of ammonium hydroxid, when a blue color indicates 
the presence of copper. 

1 Leach, u Food Inspection and Analysis," p. 70. 



CHAPTER XXVI 
ECONOMY IN PREPARATION OF FOOD; DIETARIES 

The importance of cooking food has already been dis- 
cussed (p. 121). It is owing to the practice of cooking food 
that the dietary of civilized man has been greatly en- 
larged and improved. Many kinds of food which would be 
not only unpalatable, but indigestible in the raw state, are 
rendered wholesome and nourishing by some process of cook- 
ing. So the proper cooking of food may be regarded as an 
art ; indeed, one distinction of a civilized man is that he is 
one who prepares his food by cooking. Most foods, with 
the exception of fruits, require cooking ; animal foods espe- 
cially are cooked to make them palatable and wholesome. 

In addition to what has been said on previous pages 
about cooking in the case of individual foods, since all the 
different foods have now been studied, some general state- 
ments will be more readily understood. 

In the cooking of starchy foods it will be noticed that the 
starch grains, as " put up," so to speak, by nature, are very 
close and compact in most seeds, so that they will withstand 
any natural temperature, and a moist as well as a dry climate. 
When these seeds are to be used for food they must be 
soaked with water and allowed to swell. By this treatment 
the fine particles of starchy substances will be in a much 
better condition to be attacked in the process of digestion 
by the alimentary liquids. The starch grains are rendered 
much more digestible by being cooked; there is less lia- 
bility that they shall pass through the body unchanged, for 

308 



ECONOMY IN PREPARATION OF FOOD 309 

if they are not changed to sugar by the ptyalin (see Ex- 
periment 84) of the saliva, or the juices in the stomach and 
intestines, they do not nourish the body. 

Fats undergo slow combustion in the body and are 
changed to carbon dioxid and water, thus furnishing much 
of the heat needed by the body. If these are too expensive, 
their place may, to a considerable extent, be taken by the 
carbohydrates. In any case the excess, or that which 
remains over what is actually used up in doing the work 
required of the body, is stored up, and may be drawn upon 
as a reserve. 

The fats should be taken into the system as fats and not 
as products of the destruction of fats. In the process of 
digestion in the intestine, the fat is subjected to a double 
process of emulsification and saponification, which is brought 
about by the combined action of the bile and the pancreatic 
juice. This process is interfered with, and indigestion is 
produced when overheated fats are taken into the system. 
These volatile products which are produced by the decompo- 
sition of the fats cause the familiar irritation of the eyes, 
and a disagreeable odor, when food is fried. 

In cooking an albuminous food, as an egg, if frying is the 
method of cooking used, the temperature is necessarily so 
high that the egg albumin is rendered hard and partially in- 
soluble in the digestive fluids. Oysters, 1 when satisfactorily 
cooked, are heated only to boiling, or if fried, are sur- 
rounded by a batter, which protects the albuminous tissues 
from being overheated. A high temperature also greatly 
decreases the digestibility of the gluten of grains and of 
the casein of milk, so the latter liquid is less wholesome 
when boiled. 

Beans and peas, which contain both legumin and starch, 

1 Richards and Elliot, " The Chemistry of Cooking and Cleaning," 
p. 51. 



310 SANITARY AND APPLIED CHEMISTRY 

require considerable cooking, to soften the cellulose and 
make the starch digestible. If these vegetables are cooked 
in hard water, there is danger that an insoluble compound 
shall be formed, by the combination of the legumin with 
lime or magnesia in the water ; steaming, as previously sug- 
gested, will partly obviate this difficulty. 

Again, in seeking for economy of food, the question arises, 
What food furnishes the largest amount of nutriment at the 
most reasonable cost ? As we shall see a little later, the 
amount of energy in terms of " calories " that each food 
is capable of producing, has been carefully determined, and 
this will furnish a clew to the value of different foods. For 
instance, a certain sum invested in bread will yield much 
more energy than the same sum invested in milk or in meats. 
Both the latter foods are valuable, but they are not cheap. 

To build up the tissues, a cheap form of proteid is that 
contained in peas or beans, while eggs are eight times as 
expensive, and beef five times as expensive at ordinary 
prices. 

In general, vegetable food is cheaper than animal food, 
either as a source of energy or to build up the tissues. The 
reason for this is evident when we consider that the vegeta- 
ble foods are built up from the simple substances found in air, 
water, and soil, while the food of animals consists of highly 
organized vegetable or animal substances. One author states, 
as an illustration of the comparative cost of vegetable food, 
that 2\ acres devoted to raising mutton would support a 
man for a year, while the same amount devoted to the 
growing of wheat would support 16 men for the same time. 
It may be said that as the vegetable food is so much more 
bulky it would require much more heat to cook it, but with 
the best appliances, the cost of this additional fuel would 
not counterbalance the increased cost of animal food. 

While carbohydrates are cheap constituents of food, pro- 



ECONOMY IN PREPARATION OF FOOD 311 

teids and fats are expensive. If the fat is derived from 
animal sources this is particularly true, but foods contain- 
ing cotton-seed oil, and the oil of some varieties of nuts, 
furnish fats at a reasonable price. 

There is no necessary relation between the cost of a food 
and its nutritive value, for we pay for color, size, appear- 
ance, and flavor, in foods, not for their value in feeding the 
body. There is practically as much nourishment in the cut 
of beef costing 8 cents a pound as in that costing 16 cents ; 
a fine quality of starch in the form of arrowroot or sago is 
expensive, but the same amount of starch of a different fla- 
vor made from corn is very cheap ; a Boquef ort cheese costs 
perhaps 50 cents a pound, while a cheese just as good for 
food, but made in New York State, costs only 15 cents. 

It is important that the right method of cooking should 
be selected for each food, a method that shall develop the 
agreeable flavors and make the food as digestible as possible. 
A cheap cut of beef may be made appetizing and wholesome 
by careful and skillful cooking, and it is equally true that 
an expensive cut may be made tough and tasteless by the 
ignorant cook. It is easy to spoil good food, and render it 
unwholesome by cooking it in fat, or by too slow heating. 
Potatoes maybe cooked till they are " mealy" and the sepa- 
rate starch grains glisten in the light, or they may be water- 
soaked and waxy, and consequently slow to digest. It is 
easy to prepare sour or heavy bread, overheated toast, tough 
beefsteak, or muddy coffee, but the raw material costs just 
as much as if the food product had been made wholesome 
and agreeable. 

Great economy of fuel can be secured by the use of the 
right kind of stove or range, and by utilizing such an 
appliance as a " steamer," so that half a dozen dishes can be 
cooked at one time over the same fire. This latter vessel is 
especially economical when gas, either natural or artificial, 



312 SANITARY AND APPLIED CHEMISTRY 

or gasoline is used for fuel in cooking. When the water is 
once brought to a boiling temperature in the steamer, a very 
small flame will keep it boiling, and the contents of the 
vessel will not become appreciably hotter, nor will it cook 
much quicker, if it boils much more tumultuously. Boiling 
water means 100 ° C, and it does not get any hotter, except 
under pressure. This is a fact too often forgotten by the 
cook, who is anxious to "hurry the dinner." 

Another interesting application of science to the culinary 
art is the invention of the Aladdin oven, by Edward Atkin- 
son. 1 This oven consists of a metallic chamber surrounded 
by nonconducting material, and so arranged that it can be 
heated from below with a good kerosene lamp or Rochester 
burner. Almost any food may be cooked in this oven, and 
it is especially adapted to the preparation of soups and the 
cooking of vegetables. The process depends on the use of a 
moderate heat for a long time instead of a high temperature 
for a short time, as in ordinary cooking. As the oven is 
surrounded by a nonconducting wall, the heat that is pro- 
duced cannot readily escape. This oven has been utilized 
on a large scale in preparing cheap and nutritious food for 
workmen. 

DIETARIES 

We have already discussed the two general classes of 
nutrients (p. 123) and to some extent the properties of 
each class. Most of our knowledge of the composition 
and nutritive value of food has been accumulated, in the 
United States and Europe, within the past fifty years. 
Although the analysis of milk was reported by Boussingault 
and Le Bel in 1831, 2 yet it was not till Liebig, Playfair, 

1 " The Right Application of Heat to the Conversion of Food Mate- 
rial," Proc. Am. Assoc, for Adv. Science, 1890. 

2 Atwater. ''Foods, Nutritive Value and Cost," Farmer's Bui. 
23, U. S. Dept. Agric. 



ECONOMY IN PKEPARATION OF FOOD 313 

Boeckman, and others, about the middle of the last century, 
devised new methods for the analysis of foods and feeding 
stuffs, that we began to have a definite knowledge of this 
important subject. 

With the adoption of the so-called Weende method, pro- 
posed by Henneberg in 1864, new impetus was given to this 
branch of investigation, and numerous improvements have 
been made, till now chemists generally agree on the methods 
of analysis to be employed. American food products first 
began to be investigated in 1878-1881, by Professor Atwater, 
under the auspices of the United States Fish Commission, 
and these investigations have been carried on more recently 
by agricultural colleges, the experiment stations of the va- 
rious states, and the Department of Agriculture of the gen- 
eral government. The latter department, at an expense of 
from $10,000 to $20,000 per year, for the past 10 years, has 
extended these investigations on human nutrition, till at 
the present time we have very complete data upon this 
subject. 1 

We have already learned that the analysis of a food shows 
the per cent of water, proteids, fats, carbohydrates, and min- 
eral salts, which it contains, and each of these, with perhaps 
the exception of water, has its food value. In order to com- 
pare the different foods, and calculate the relative amount 
of energy that can be obtained from them, the ordinary 
method is to determine the "heat units," or "calories/' that 
can be produced by the combustion, under standard condi- 
tions of a given amount of food. Although the results are not 
exactly the same when food is oxidized in the body to 
produce energy, and when it is burned in a calorimeter to 
produce heat, yet this method is convenient for classification 
and computation of the relative value of foods. 

1 Atwater and Woods. u Chem. Comp. of Am. Food Materials," 
Bui. 28, U. S. Dept. Agric, Office of Exp. Stations. 



314 SANITARY AND APPLIED CHEMISTRY 

A calorie l is the amount of heat that is required to raise 
the temperature of one kilogram of water from 0° to 1° C, 
or approximately the amount of heat that would be required 
to raise one pound of water 4° F., and is equal to 3084 foot- 
pounds. The "fuel value" means the total calories obtained 
by the combustion of any food substance within the body. 
Considering the ordinary food materials, the following esti- 
mate has been made for the average amount of heat and 
energy or the "fuel value" of each of the classes of 
nutrients : — 

One pound of protein gives .... 1860 calories. 

One pound of fats gives 4220 calories. 

One pound of carbohydrates gives . . . 1860 calories. 

From this it will be seen that a pound of protein of lean 
meat, for instance, is about equal to a pound of sugar or starch, 
in yielding heat and mechanical energy, and that fats have 
a fuel value about two and a quarter times that of the carbo- 
hydrates or protein. 

From the analyses of foods, to which reference has been 
made, it is possible to calculate the fuel value of a given 
amount of any food or of the rations supplied to a number of 
people. 

Experiments have also been carried on by W. O. Atwater, 
at the Wesleyan University, in what is known as a " res- 
piration calorimeter." In this apparatus, which is a small 
closed room, the experimenter remains for several days, and 
all the food, air, and water used is weighed and passed in 
to him, and all the products given off from the body are 
also weighed and analyzed. A careful record is also taken 
of the temperature, and if the experimenter works to exer- 

1 See "Foods, Nutritive Value and Cost," Atwater, also "Practical 
Dietetics," Thompson, also "Air, Water, and Food," Richards and 
Woodman. 



ECONOMY IN PREPARATION OF FOOD 315 

cise his muscles, a record is made of the mechanical work 
accomplished. " The main value of the experiments so far 
conducted in this calorimeter consists in the actual demon- 
stration that the law of conservation of energy operates 
within the body in precisely the same manner as it does 
outside." In man it was found that the measured energy 
of the food consumed by the subject within the calorimeter 
was within 1 % of the calculated or theoretical energy. 

Having a knowledge of the composition of food, and a 
method for finding its value as an energy producer, we are in 
a position to study the food of different individuals or classes 
of people, or to study dietaries. A dietary, then, would be 
a known amount of food of known composition, per day per 
person, and a standard dietary would be such a combina- 
tion of materials as furnishes a sufficient amount of each of 
the nutrient substances to fully sustain the body. 

Professor Voit of Munich was one of the first to pre- 
pare standard dietaries, and his work has been supplemented 
by a large amount of work in the United States, espe- 
cially within the last ten years. 

It has been recently pointed out that there are two meth- 
ods of estimating dietaries. One method is by studying 
the food consumption of classes of people or individuals, 
when they have a free choice of food, or when they procure 
such food as their circumstances allow them to buy. The 
other method contemplates the feeding to classes of individ- 
uals, or to selected persons, certain foods of known weight 
and composition, and studying the nitrogen balance, as it is 
called ; that is, the amount of nitrogen taken into the body, 
daily, in the food, and the amount excreted. If there is 
more nitrogen excreted from the body than taken in, the 
system is evidently not fully nourished. If there is a slight 
excess of nitrogen maintained, the food is sufficient for the 
amount of work done by the individual. An excess of 



316 



SANITARY AND APPLIED CHEMISTRY 



nitrogenous material, or of fat, may be stored in the body 
for use in emergencies. 

Eeturning to the ordinary method of studying dietaries, 
some examples may be given of the results observed by 
different chemists : 1 — 









Carbo- 


Fuel 


Nutritive 


DIETARIES 2 


Protein 


Fats 


HYDRATES 


Value 


Katio 




Lbs. 


Lbs. 


Lbs. 


Calories 


lto 


Well-fed tailors, Eng- 












land, Playfair . . 


.29 


.09 


1.16 


3055 


4.7 


Blacksmiths, England, 












Playfair 


.39 


.16 


1.47 


4115 


4.7 


Well-fed mechanics, Mu- 












nich, Voit .... 


.34 


.12 


1.06 


3085 


4.0 


Brickmakers, Munich, 












diet mainly corn meal 












and cheese, Ranke . 


.37 


.26 


1.49 


4540 


5.6 


Brickmakers, Massachu- 












setts, very severe work 


.40 


.81 


2.54 


8850 


11.0 


Professional men, Mid- 












dletown, Ct., Atwater 


.27 


.34 


1.08 


3925 


6.Q 


University professors, 












Munich, light exercise, 












Ranke 


.22 


.22 


.53 


2325 


4.7 



In the above table the nutritive ratio, mentioned in the 
last column, is the ratio of the protein to the sum of all the 
other nutritive ingredients. The fuel value of the fats, as pre- 
viously noted, is two and a quarter times that of the protein 
and carbohydrates, so in the calculation the quantity of fats is 
multiplied by two and one fourth, and the product is added 

1 Chittenden, " Physiological Economy in Nutrition"; also At- 
water, loc. cit. 

2 Per man per day. 



ECONOMY IN PREPARATION OF FOOD 



317 



to the carbohydrates. This sum, divided by the weight of 
the protein, gives the nutritive ratio. Thus, in the first 
dietary quoted, the ratio of protein to fats and carbohy- 
drates is as 1 to 4.7. 

Some standard dietaries have been compiled by Atwater, 
and represent what is believed by the several authors to 
be the amount needed by persons with different degrees of 
labor. (The amounts are expressed in grams.) 





Protein 


Fats 


Carbohy- 
drates 


Total 


Fuel Value, 
or Calories 


Children, 6 to 15 . 


75 


43 


325 


443 


2041 


Women, at moderate 












work, Voit . . . 


92 


44 


400 


536 


2426 


Man, at moderate 












work, Voit . . . 


118 


56 


500 


674 


3055 


Man, at hard work, 












Voit 


145 


100 


450 


695 


3370 


Hard labor, Playfair 


185 


71 


568 


824 


3748 


Man, at moderate 












work, Atwater . 


125 


125 


450 


700 


3520 


Man, at hard work, 












Atwater . . . 


150 


150 


500 


800 


4060 



Experiment 165. Study the food used by a family or club 
for a period of several weeks. Note the actual weight of 
all food purchased, the cost, and the number of individual 
meals taken. From the tables given by Atwater, compute 
the total amount of protein, fats, and carbohydrates consumed, 
and the amount per day per capita. By the use of the same 
tables estimate the " fuel value " of the food, and the nutri- 
tive ratio. Tabulate the results as in the table quoted from 
Mrs. Eichards on page 319. 

The daily amount of solid food consumed by the adult 
male is 50 oz. to 60 oz., and the water used is about the 



318 SANITARY AND APPLIED CHEMISTRY 

same. In case of severe labor this amount of food would be 
increased to 75 oz. ? the addition being mostly in fats and car- 
bohydrates. 1 The standard ratio for health, of protein to fuel 
ingredients, has been placed at 1 to 5.8 by the Experiment 
Stations of the Department of Agriculture. 

According to the standard dietaries given above, and 
many others that might be quoted, an average man doing 
light work would consume 116 g. of protein, with suffi- 
cient fat and carbohydrates, to give 3050 calories; many 
authorities would decrease this as low as 100 g. of protein. 
This could be obtained from a great variety of diet, either 
largely vegetable, or with a moderate amount of animal 
food. 

From some recent experiments by Chittenden, 2 and oth- 
ers, upon several groups of persons, some of whom lived 
sedentary lives, and others of whom were athletes and sol- 
diers, it was shown that it was possible to maintain the 
nitrogen balance and remain in good health with consid- 
erably less food, especially of the proteid class, than 
the accepted dietary standards would indicate. On a diet 
containing only 42 to 55 g. of proteid matter, instead of 
116 to 121, and enough carbohydrates and fats to make 
1750 calories, instead of 3050, the men lived and carried on 
their daily work for several months. This would indicate 
that there is a tendency to eat more food than necessary, 
and thus to overburden the excretory organs. 

The following ideal ration of solid food is given by Mrs. 
E. H. Richards: 3 — 

1 Thompson, " Practical Dietetics," p. 20. 

2 " Physiological Economy in Nutrition"; " Economy in Food," 
Century Magazine, Vol. 70, p. 859. 

3 " Chem. Com. of Am. Food Material." Bui. 28, U. S. Dept. 
Agric, Office of Exp. Stations. Also see Farmer's Bui. 23, U. S. 
Dept. Agric. 



ECONOMY IN PKEPAKATION OF FOOD 



319 



Material 


Amount 
Grams 


Proteid 


Fat 


Carbo- 
hydrates 


Calories 


Bread .... 
Meat .... 
Oysters .... 
Breakfast Cocoa 

MUk 

Broth .... 
Sugar .... 
Butter .... 


453.6 
226.8 
226.8 

28.3 
113.4 
453.6 

28.3 
14.17 


31.75 
34.02 
12.52 
6.60 
3.63 
18.14 

.14 


2.26 
11.34 
2.04 
7.50 
4.42 
18.14 

12.27 


257.28 

9.60 

4.88 

90.72 

27.36 


1206.82 
243.72 

70.01 
135.42 

75.55 
316.21 
112.17 
118.62 


Total . . . 




106.80 


57.97 


389.84 


2574.60 



Here the amount of proteid is nearly 107 g. or about the 
average suggested by the best authorities. 

In studying dietaries, it is also a practical question to 
ascertain what the cost of food per day per man should be. 
The habits of people differ so widely, that while in some 
countries good and sufficient food can be obtained at 10 to 
15 cents per day per capita, in other localities as much as 
35 cents per day is needed to procure satisfactory food. 
The following summary x of cost of food in different locali- 
ties, and under varying conditions of life, and showing the 
amount of food wasted, is of interest: — 



Cost of Food 
Purchased 



Teacher's family, Illinois . 
Professional men, Connecticut 
Mechanics' Boarding Club, 

Illinois 

Mechanic's family, Indiana 
Mechanic's family, Tennessee 
Students' Club, Kansas 2 . 



Cents 
27 
25 

23 
26 
16 

18 



Calories 



3975 
3530 

3720 
3840 
4435 
3437 



Calories 
Wasted 



700 
100 

330 
555 
345 



Nutritive 
Eatio 



1:6.9 
1:6.8 

1:6.1 
1:7.9 
1:8.1 
1:7.6 



i Bui. 91, U. S. Dept. of Agric, Bu. Chem., 1900. 
2 Trans. Kan. Acad, of Science, Vol. XIX. 



320 



SANITARY AND APPLIED CHEMISTRY 



As some of these figures were obtained several years ago, 
they would not indicate the cost of living at the present 
time, as similar experiments have shown that it has in- 
creased, within a few years, from 25 % to 30 %. 

The waste of food referred to covers the necessary loss 
from skins, seeds, bones, etc. ; and evidently, from the great 
difference in different cases, it also covers a large amount 
of unnecessary waste. 

From statistics collected in this country, especially in 
Massachusetts, and in Europe, an idea can be obtained of 
the proportion of income that is ordinarily used for the 
purchase of food by families in different circumstances : * — 





Income 


Per Cent 
expended 
for Food 


Germany 
Workingmen 


Dollars 
225-300 
450-600 
750-1100 

500 

350-400 

450-600 

600-750 

750-1200 

Above 1200 


62 


Middle class 


55 


Well-to-do 


50 


Great Britain 
Workingmen 


61 


Massachusetts 
Workingmen 


64 


Workingmen 


63 


Workingmen 


60 


Workingmen . 


56 


Workingmen 


51 







When the income is small, considerably more than one 
half is expended for actual food. This surely leaves a very 
small amount for rent, clothing and the other necessaries of 
life. Since a sufficient quantity of wholesome food is of the 
utmost importance, the poor man is justified in expending 

1 Farmer's Bui. 23, U. S. Dept. Agric. 



ECONOMY IN PREPARATION OF FOOD 321 

more than half of his income to provide his family with that 
which they need to give them health and strength. It is 
unfortunately true, however, that even the most intelligent 
people know less of the source, uses, and actual value of 
their food for fulfilling its important purpose, than they do 
of almost any of the other daily necessities. 

It is estimated that at least 10 % of the income is 
squandered not only by the well-to-do, but frequently also 
by those who have a very small income and so can ill afford 
it, in expensive food material which affords little nutrition, 
in unsatisfactory methods of preparation, in selecting foods 
out of season, by throwing away much valuable food material, 
and by using badly constructed cooking appliances. Much 
careful investigation is needed along these economic lines, 
and painstaking instruction will ultimately improve these 
conditions which are at present so much deplored. 



BIBLIOGRAPHY 

The following books and periodicals will be found con- 
venient for reference. A more complete bibliography on 
foods is found under the individual topics in " Leach on 
Food Inspection and Analysis." An excellent bibliog- 
raphy on the general subjects discussed in this book may 
be found in Richards and Woodman's " Air, Water, and 
Food." 



Authors 


Books 


Publishers 


Abady. 


Gas Analysis Manual. 


Spon & Chamberlain, New 
York. 


AUen. 


Commercial Organic Anal- Blakiston's Sons & Co., 




ysis. Vol. 1, 2, 3, 4. Philadelphia. 


Bailey. 


Mineral Waters of Kansas. Kans. State Univ., Geolog. 




Vol* VH. Survey. 


Bailey and Cady. 


Laboratory Guide to Study Blakiston's Sons & Co., 




of Qualitative Analysis. 1 Philadelphia. 


Barry. 


Hygiene of the School- Silver, Burdett & Co., 




room. Boston. 


Bartley. 


Medical Chemistry. i Blakiston's Sons & Co., 




Philadelphia. 


Barwise. 


Bacterial Purification of.C. Lockwood & Son, Lon- 




Sewage. don. 


Battershall. 


Food Adulteration and its.E. & F. N. Spon, New 




Detection. York. 


Benedict. 


Chemical Lecture Experi- Macmillan Co., New York. 




ments. 


Benedikt and 


Chemistry of Coal Tar 'Geo. Bell & Sons, London, 


Knecht. 


Colors. 1889. 


Bergey. 


Methods for Determination Smithsonian Inst., TVash- 




of Organic Matter in Air. ington. 



323 



324 



BIBLIOGRAPHY 



Authors 


Books 


Publishers 


Billings. 


Ventilation and Heating. 


Engineering Record, New 
York. 


Bissell. 


Household Hygiene. 


Hodges, New York. 


Black. 


Forty Years in the Medical 


Lippincott Co., Philadel- 




Profession. 


phia. 


Blyth. 


Dictionary of Hygiene and 
Puhlic Health. 


Griffin & Co., London. 


Blyth. 


Food, Composition and 
Analysis. 


Griffin & Co., London. 


Bowditch. 


Coal Gas, Analysis, Valua- 
tion, Purification and 
Use of. 


E. & F. N. Spon, London. 


Catlin. 


Baking Powders. 


Rumf ord Chemical Works, 
Providence, R. I. 


Chittenden. 


Studies in Physiological 
Chemistry. 


Scribner's Sons, New York. 


Chittenden. 


Physiological Economy in 
Nutrition. 


Stokes Co., New York. 


Church. 


Food. 


Chapman & Hall, London. 


Clarke. 


Elementary Chemistry. 


American Book Co., New 
York. 


Crook. 


Mineral Waters of United 


Lea Brothers & Co., Phila- 




States and their Thera- 


delphia. 




peutic Uses. 


* 


Dammer. 


Handbuch der Chemischen 
Technologic 


Ferdinand Enke, Stuttgart. 


Davis. 


Potable Waters. 


The Author, Des Moines. 


Davis. 


Chemistry for Schools. 


Scott, Foresman & Co., 
Chicago. 


Duckwall. 


Canning and Preserving. 


Pittsburg Printing Co., 
Pittsburg Pa. 


Eccles. 


Food Preservatives and 


Van No strand & Co., New 




their Proper Uses. 


York. 


Effront. 


Enzymes and their Appli- 
cation. 


Wiley & Sons, New York. 


Eliot. 


Elementary Manual of 


American Book Co., New 




Chemistry. 


York. 


Erdmann. 


Lehr Buch der Anorgan- 


Vieweg & Sohn, Braun- 




ischen Chemie. 


schweig. 



BIBLIOGRAPHY 



325 



Authors 


Books 


Publishers 


Fox. 


Sanitary Examinations of 
Water, Air, and Food. 


Churchill Co., London. 


Fr alike. 


Die Chemie der Kiiche. 


Van Voorst, London. 


Freer. 


Microorganisms in Water. 


Allyn & Bacon, Boston. 


Frankland, P. and 

G. C. 
Frankland, Mrs. 


Bacteria in Daily Life. 


Longmans & Co., London. 


Elements of Chemistry. 


Longmans & Co., London. 


Percy. 






GiU. 


Gas and Fuel Analysis for 
Engineers. 


Wiley & Son, New York. 


Green. 


Food Products of the 
World. 


Hotel World, Chicago. 


Groves and Thorp. 


Chemical Technology. 


Blakiston's Sons & Co., 




Vol. I. Fuels. 


Philadelphia. 


Groves and Thorp. 


Chemical Technology. 


Blakiston's Sons & Co., 




Vol. II. Lighting. 


Philadelphia. 


Groves and Thorp. 


Chemical Technology. 


Blakiston's Sons & Co., 




Vol. III. Gas Lighting. 


Philadelphia. 


Hardin. 


Liquefaction of Gases. 


Macmillan Co., New York. 


Harrington. 


Practical Hygiene. 


Lea Brothers & Co., Phila. 


Hartshorne. 


Our Homes. 


Blakiston's Sons & Co., 
Philadelphia. 


Harrop. 


Flavoring Extracts with 


Harrop & Co., Columbus, 




Essences, Sirups, and 


Ohio. 




Coloring. 




Hassall. 


Food Adulterations, and 


Longmans, Green & Co., 




Methods for Detection. 


London. 


Hassler. 


Essentials of Chemistry. 


Sanborn & Co., Boston. 


Hazen. 


Filtration of Public Water 
Supply. 


Wiley & Sons, New York. 


Holland. 


Medical Chemistry and 


W. B. Saunders & Co., 




Toxicology. 


Philadelphia. 


Hutchison. 


Food and Dietetics. 


Wm. Wood & Co., New 
York. 


Jago. 


Science and Art of Bread- 


Simpkin, Marshall, Hamil- 




making, Chemistry, and 


ton, Kent & Co., London. 




Analysis of Wheat Flour. 




Jones. 


Principles of Inorganic 
Chemistry. 


Macmillan Co., New York. 



326 



BIBLIOGRAPHY 



Authors 



Jones. 

Kent. 
Kenwood. 

Konig. 



Lankester. 
Lassar-Cohn. 

Leach. 

Leeds. 

Leffmann and Beam. 

Leffmann. 



Lekowitsch. 

Letherby. 

Lewes. 
Mallet. 

Mason. 
Newth. 

Nichols. 

Paasche. 

Pasteur. 
Paul. 

Pavy. 

Peters. 



Books 

Elements of Inorganic 

Chemistry. 
Steam Boiler Economy. 
Public Health Laboratory 

Work. 
Chemie der Menschlichen 

Nahrungs und Geniiss- 

mittel. 
Lectures on Food. 
Chemistry in Daily Life. 

Food Inspection and Analy- 
sis. 

Treatise on Ventilation. 

Select Methods of Food 
Analysis. 

Examination of Water for 
Sanitary and Technologi- 
cal Purposes. 

Chemical Technology and 
Analysis of Oils, Fats, 
and Waxes, 2 vols. 

On Food. 

Air and Water. 
Water Analysis. 
Water Supply. 
Chemical Lecture Experi- 
ments. 
Water Supply. 

Zucker industrie und Zuck- 
erhandel der Welt. 

Studies on Fermentation. 

Payen's Industrial Chem- 
istry. 

Food and Dietetics. 

Modern Chemistry. 



Publishers 

MacmillanCo., New York. 

Wiley & Sons, New York* 
H. K. Lewis, London. 

Julius Springer, Berlin. 



Hardwicks Co., London. 
Lippincott Co., Philadel- 
phia. 
Wiley & Sons, New York. 

Wiley & Sons, New York. 
Blakiston's Sons & Co., 

Philadelphia. 
Blakiston's Sons & Co., 

Philadelphia. 

Macmillan Co., New York. 



Bailliers, Tindall & Co., 

London. 
Methuen & Co., London. 
National Bd. of Health. 
Wiley & Sons, New York. 
Longmans Green & Co., 

London. 
Wiley & Sons, New 

York. 
Gustav Fischer, Jena. 

Macmillan Co., London. 
Longmans, Green & Co., 

London. 
Wood & Co., New York. 
Maynard, Merrill & Co., 

New York. 



BIBLIOGRAPHY 



327 



Authors 


Books 


Publishers 


Pharmacopoeia of 


8th Decennial Revision. 


Blakiston's Sons & Co., 


United States. 




Philadelphia. 


Price. 


Handbook on Sanitation. 


Wiley & Sons, New York. 


Rafter. 


Microscopical Examina- 


Van Nostrand Co., New 




tion of Potable Water. 


York. 


Rafter. 


Treatment of Septic Sew- 


Van Nostrand Co., New 




age. 


York. 


Rafter and Baker. 


Sewage Disposal in United 


Van Nostrand Co., New 




States. 


York. 


Ramsay. 


Gases of the Atmosphere. 


Macmillan Co., London. 


Redwood. 


Petroleum and its Prod- 
ucts, Vol. I and II. 


Griffin & Co., London. 


Remsen. 


Introduction to Study of 
Chemistry, 7th Ed. 


Holt & Co., New York. 


Richards. 


Food and Diet. 


Whitcomb & Barrows, Bos- 
ton. 
Wiley & Sons, New York. 


Richards. 


Cost of Living. 


Richards and Elliott. 


The Chemistry of Cooking 


Whitcomb & Barrows, Bos- 




and Cleaning. 


ton. 


Richards and Wood- 


Air, Water, and Food. 


Wiley & Sons, New York. 


man. 
Rideal. 


Water and its Purification. 


Lippincott Co., Philadel- 
phia. 


Rolfe. 


The Polariscope. 


Macmillan Co., New York. 


Sad tier. 


Industrial Organic Chemis- 


Lippincott Co., Philadel- 




try. 


phia. 


Schulz. 


Die Mineral-Trinkquellen 
Deutschlands. 


J. Abel. Greifswald. 


Sedgwick. 


Principles of Sanitary Sci- 
ence and Public Health. 


Macmillan Co., New York. 


Simon. 


Manual of Chemistry. 


Lea Brothers & Co., Phila- 
delphia. 


Smith. 


Foods. 


Appleton & Co., New York. 


Snyder. 


Chemistry of Plant and 
Animal Life. 


Macmillan Co., New York. 


Spencer. 


Handbook for Sugar Manu- 
facturers and Chemists. 


Wiley & Sons, New York. 


Stevenson and Mur- 


Treatise on Hygiene and 


Blakiston's Sons & Co., 


pby- 


Public Health. 


Philadelphia. 



328 



BIBLIOGEAPHY 



Authors 


Books 


Publishers 


Sulz. 


Treatise on Beverages. 


Sulz & Co., New York. 




Packing House Industries, 


International Text Book 




Cottonseed Oil, Manufac- 


Co., Scranton, Pa. 




ture of Leather and Soap. 




Thompson, W. G. 


Practical Dietetics. 


Appleton & Co., New York. 


Thorp. 


Outlines of Industrial 
Chemistry. 


Macmillan Co., New York. 


Thresh. 


The Examination of Waters 


Blakiston's Sons & Co., 




and Water Supplies. 


Philadelphia. 


Thudicum. 


Cookery, its Art and Prac- 
tice. 
Coffee from Plantation to 


F. Warne & Co., London. 


Thurber. 


American Grocer Pub. As- 




Cup. 


sociation, New York. 


Tollens. 


Handbuch der Kohlenhy- 
drates. 


E. Trewendt, Breslau. 


Tucker. 


Manual of Sugar Analysis. 


Van Nostrand, New York. 


Vaughan and Novy. 


Cellular Toxins. 


Lea Bros. & Co., Phila. 


Venable. 


History of Chemistry. 


Heath Co., Boston. 


Wanklyn. 


Water Analysis. 


Triibner & Co., London. 


Wanklyn. 


Bread Analysis. 


Triibner & Co., London. 


Wanklyn. 


Milk Analysis. 


Triibner & Co., London. 


Watts. 


Dictionary of Chemistry, 


Longmans, Green & Co., 




4 Vols. 


London. 


Weiehmann. 


Sugar Analysis. 


Wiley & Sons, New York. 


Whipple. 


Microscopy of Drinking 






Water. 


Wiley & Sons, New York. 


Wiley. 


Agric. Chem. Analysis, 
3 Vols. 


Chem. Pub. Co., Easton. 


Williams. 


Chemistry of Cookery. 


Appleton & Co. , New York. 


Willoughby. 


Hygiene for Students. 


Macmillan Co., London. 


Winton and Moeller. 


The Microscopy of Vegeta- 
ble Foods. 


Wiley & Sons, New York. 


Wood. 


United States Dispensa- 


Lippincott Co., Philadel- 




tory. 


phia. 


Yeo. 


Food in Health and Disease. 


W. T Keener & Co., Chi- 
cago. 


Zipperer. 


Manufacture of Chocolate. 


Spon & Chamberlain, New 
York. 



BIBLIOGRAPHY 



329 



PERIODICALS 



Authors 


Subjects 


Publications 


Abel. 


Sugar as Food. 


U.S. Dept. Agri. Farmer's 
Bui. 13. 


Abel. 


Beans and Peas and Other 


U.S. Dept. Agri. Office 




Leguminous Food. 


Exp. Sta. Bui. 44. 


Amer. Chem. Jour., 






Vols. 1-34. 






Atkinson. 


Cooking of Food. 


U.S. Dept. Agri. 


Atwater. 


Experiments in the Con- 


U.S. Dept. Agri. Exp. Sta. 




servation of Energy. 


Bui. 63. 


Atwater. 


Bread and Principles of 


U.S. Dept. Agri. Farmer's 




Bread Making. 


Bui. 112. 


Atwater. 


Foods, Nutritive Value 


U.S. Dept. Agri. Farmer's 




and Cost. 


Bui. 23. 


Atwater, Benedict. 


Exp. in Metabolism of 


U.S. Dept. Agri. Office 




Matter and Energy in 


Exp. Sta. Bui. 69. 




the Human Body. 




Atwater, Woods, 


Metabolism of Nitrogen 


U.S. Dept. Agri. Exp. Sta. 


Benedict. 


and Carbon in the 
Human Organism. 


Bui. 63. 


At wood. 


A Study of Cider Making. 


U.S. Dept. Agri. Bu. of 
Chem, Bui. 71. 


Atwood. 


Chemical Composition of 


U.S. Dept. Agri. Bu. of 




Apples and Cider. 


Chem. Bui. 88. 


Bailey. 


Recent Progress in the Salt 


Internationales Kong, fuer 




Industry in the U.S. 


angewandte Chem. 1901. 


Bigelow. 


Composition of American 


U.S. Dept. Agri. Div. 




Wines. 


Chem. Bui. 59. 


Bigelow and 


Some Forms of Food Adult. 


U.S. Dept. Agric. Bu. Chem. 


Howard. 




Bui. 100. 


Bigelow. 


Food and Food Control. 


U.S. Dept. Agri. Bu. Chem. 
Bui. 69. Pt. 2 & 4. Bui. 
83, Pt. 2. 


Bigelow. 


Analysis of Foods. 


U.S. Dept. Agri. Bu. of 
Chem. Bui. 65. 


Bigelow, Gore. 


Studies in Apples. 


U.S. Dept. Agri. Bu. of 
Chem. Bui. 94. 



330 



BIBLIOGRAPHY 



Authors 


Subjects 


Publications 


Bigelow, Gore, 


Studies on Peaches. 


U.S. Dept. Agri. Bu. of 


Howard. 




Chem. Bui. 97. 


Causse. 


Recherches sur la contami- 
nation des Eaux. 


Storck, Lyons. 


Chase, Tolman, 


Chemical Composition of 


U.S. Dept. Agri. Bu. of 


Munson. 


some Tropical Fruits and 
their Products. 


Chem. Bui. 87. 


Corbett. 


Tomatoes. 


U.S. Dept. Agric. Farmer's 
Bui. 200. 


Duggan. 


Cultivation of Mushrooms. 


U.S. Dept. Agric. Farmer's 
Bui. 204. 


Gibson. 


Dietary Studies. 


Univ. of Mo. Exp. Sta. 
Bui. 31. 


Grindley 


Losses in cooking Meat, 


U.S. Dept. Agric. 0. Ex. Sta. 




etc. 


Buls. 102, 141, 162. 


Jour. Amer. Chem. 






Soc. Vols. 1-27. 






Jour. Chem. Soc. 






Vols. 38-64. 






Jour, of Soc. of Chem # 






Industry, Vols. 1-24. 






Jordan. 


Dietary Studies in Maine 


U.S. Dept. Agri. Office 




State College. 


Exp. Sta. Bui. 37. 


Kebler. 


Adulterated Drugs and 


U.S. Dept. Agri. Bu. of 




Chemicals. 


Chem. Bui. 80. 


Langworthy. 


Eggs and their uses as 


U.S. Dept. Agri. Farmer's 




Food. 


Bui. 128. 


Leffman. 


Milk Inspections and Milk 


Medical News, Feb. 2, 




Standards. 


1895. 


Logan. 


The Underground Waters. 


Miss. Agri. Exp. Sta. Bui. 

89. 
Exp. Sta. Bui. 66. 


Mallet. 


Creatin and Creatinin. 


McFarlane. 


Flavoring Extracts. 


Int. Rev. Dept. Canada, 
Bui. 89, etc. 


Miller. 


Baking Powders. 


Fla. Ag. Ex. Sta. Bui. 52. 


Munroe. 


Chemicals and Allied Prod- 


12th Census U.S. No. 210, 




ucts. 


Jun. 25, 1902. 


Munson, Colman, 


Fruits and Fruit Products. 


U.S. Dept. Agri. Bu. of 


Howard. 




Chem. Bui. 66. 



BIBLIOGKAPHY 



331 



Authors 


Subjects 


Publications 


Norton. 


Food Adult, in Ark. 


Ark. Ag. Ex. Sta. Bui. 88. 


Palmer. 


Chemical Survey of Wa- 
ters of Illinois. 


Univ. of 111. 


Parola. 


Canned Fruit, etc. 


U.S. Dept. Agric. Farmer's 
Bui. 203. 


Proceedings Int. 






Congress Appl. 






Chem. 




Berlin, 1903. 


Richardson. 


Foods and Food Adulter- 


U.S. Dept. Agri. Bu. of 




ants. 


Chem. Bui. 13, Prt. 2. 


Robinson. 


Breakfast Foods. 


Mich. Exp. Sta. Div. of 
Chem. Bui. 21. 


Short. 


Fat in Milk. 


Univ. of Wis. Agri. Exp. 
Sta. Bui. 16. 


Slosson. 


Composition of Prepared 
Cereal Foods. 


Wyom. Exp. Sta. Bui. 33. 


Smith. 


Sewage Disposal on the 
Farm and Protection of 
Drinking Water. 


Farmer's Bui. 43. 


Snyder. 


Studies in Bread and 
Bread Making. 


Minn.Ag. Exp.Sta.Bul.101. 


Snyder. 


Milling Tests of Wheat. 


Minn. Ag. Ex. Sta. Bui. 90. 


Snyder. 


Digestibility and Nutritive 
Value of Bread. 


Minn. Ag. Ex. Sta. Bui. 126. 


Snyder, Frisky, 


Composition and Digesti- 


Minn. Ag. Ex. Sta. Bui. 43. 


Bryant. 


bility of Potatoes and 
Eggs. 




Snyder, Voorhees. 


Bread and Bread Making. 


Minn. Ag. Ex. Sta. Bui. 67. 


Squibb. 


Alcohol. 


U.S. Pharm. 1890. 


Stone. 


Dietary Studies. 


Purdue Univ. Bui. 32. 


Taylor. 


Food Products. 


U.S. Dept Agri. Div. 
Microsc, Vol. 1. 


Teller. 


Chemistry of Wheat. 


Ark. Ag. Ex. Sta. Buls. 42, 
53. 


Tolman, Munson. 


Olive Oil and its Substi- 


U.S. Dept. Agri. Bu. of 




stute. 


Chem. Bui. 77. 


Wait. 


Effects of Muscular Work 
upon Digestibility of 
Food and Metabolism 
of Nitrogen. 


Exp. Sta. Bui. 89 & 117. 



332 



BIBLIOGBAPHY 



Authors 


Subjects 


Publications 


Wedderburn. 


Food Adulteration. 


U.S. Dept. Agri. Div. of 
Chem. Bui. 25. 


Wedderburn. 


Food and Drug Adultera- 


U.S. Dept. Agri. Div. of 




tion Laws. 


Chem. Bui. 41. 


Weida. 


Analysis of Chocolate and 
Cocoa. 


Univ. of Kans. 


Wiley. 


American Wines at the 


U.S. Dept. Agri. Bu. of 




Paris Exposition, 1900. 


Chem. Bui. 72. 


Wiley. 


Foods and Food Adulter- 


U.S. Dept. Agri. Div. of 




ants. 


Chem., Bui. 13. Prts. 4, 
5, 6, 7, 8, 9. 


Wiley. 


Sweet Cassava. 


U.S. Dept. Agri. Bu. of 
Chem. Bui. 44. 


Wiley. 


Manufac. of Starch from 


U.S. Dept. Agric. Div. 




Potatoes and from Cas- 


Chem. Bui. 58. 




sava. 




Wiley. 


Zinc in Evaporated Apples. 


U.S. Dept. Agri. Div. of 
Chem. Bui. 48. 


Williams. 


Food Analysis. 


U.S. Dept. Agri. Bu. of 
Chem. Cir. 20. 


Woods, Merrill. 


Investigations on Digesti- 


U.S. Dept. Ag. Office Exp. 




bility and Nutritive 


Sta. Bui. 85. 




Value of Bread. 




Woods. 


Meats, Composition and 


U.S. Dept. Agri. Farmer's 




Cooking. 


Bui. 36. 



STATE REPORTS 

Conn. Agri. Exp. Sta. Reports for 1887, 1897, 1898, 1899; 1900, parts 2 & 4 ; 

1901, 1902, parts 3 & 4 ; 1903, parts 2, 4, 5 ; 1904, parts 2 & 5. 
Illinois State Board of Health, Sanitary Investigations; 1901. 
Kansas State Board of Agriculture ; 1887 to 1904. 
Kansas Academy of Science, Vols. 1-20. 

Mass. State Board of Health, 1883, 1890, 1891, 1892, 1893, 1904. 
Minn. Dairy and Food Commission, 1905. 
National Board of Health Report, 1882, &c. 
N.Y. State Bd. Health Reports. 
New Hampshire State Board of Agriculture, Vol. 13. 
Wisconsin Dairy and Food Commission, Nos. 5, 6, 7. 



INDEX 



Acid, acetic in vinegar, 304. 

benzoic in foods, 304. 

citric, 217, 247. 

lactic, 246. 

malic in fruits, 216, 223. 

salicylic in foods, 304. 

tartaric, 217. 

tartaric, manufacture of, 217. 
Acidity of fruits, 216. 
Adulteration of milk, 250. 
Adulteration of wine, 277. 
Aerated bread, 156. 
Air, ammonia in, 14. 

amount, necessary for respiration, 
41. 

composition of, 4. 

contamination of, by combus- 
tion, 40. 

determination of carbon dioxid 
in, 11. 

dew-point, 7. 

dust in air, 16, 17. 

ground, 20. 

humidity of, 7. 

hydrogen sulfid in, 14. 

in the lungs, 6. 

in public buildings, 41, 42. 

infectious diseases propagated 
in, 19. 

mechanical mixture, 5. 

methods of analysis, 6. 

moist, weight of, 8. 

nitric acid in, 14. 

of crowded rooms, 39. 

ozone in, 15. 

substances in suspension, 16. 

vitiated, how, 5. 

weight of liter, 7, 8. 
Aladdin oven, 312. 



Albuminoid ammonia in water, 70. 
Albuminous foods, 309. 

cooking of, 309. 
Albuminous substances, 230. 

function of, 230. 
Albumins, 229. 
Alcohol, as food, 287. 

from bread, 170, 171. 

manufacture of, 283, 284. 

physiological action of, 286, 287. 

properties of, 271. 
Alcoholic beverages, 271. 

per capita consumption, 271. 

sources of, 272. 
Algse, 210. 
Almonds, 227. 

bitter, 227. 
Alum, action of, on system, 163. 

in bread, 177, 178. 
Alum baking powders, 163. 

composition of, 162. 
Amides, 230. 
Ammonia, in the air, 14. 

free in water, 70. 
Ammonium carbonate, 155. 

use of, in baking, 155. 
Amygdalen, 227. 
Analysis of coals, 29. 
Analysis of gases (table), 5, 6. 
Aniline, blue, 105. 
Animal food, per capita, use of, 232. 
Anthracite coal, 28. 
Apples, 213. 

flavor of, 213, 214. 

ripening of, 213. 
Argol, 217, 274. 
Argon, discovery of, 2, 3. 
Arrowroot, 141. 
Arsenic in wall paper, 19. 
Artesian well water, 63. 
Asparagus, 209. 



333 



334 



INDEX 



Atmosphere, 1. 

Galileo's experiments, 1. 
history of, 1. 

Lavoisier's experiments, 2. 
Priestley and Scheele's experi- 
ments, 2. 
Rayleigh's and Ramsay's ex- 
periments, 2. 
Atwater, experiments by, 314. 



Babcock tester, the, 244. 
Baking bread, 171. 
Baking crackers, 171. 
Baking powders, 158-164. 

age of, 158. 

manufacture of, 164. 

use of, in baking, 158. 
Bananas, 144. 

composition of, 145. 

cultivation of, 144. 

digestibility of, 146. 

food value of, 145. 

industry, 145. 
Banana flour, 146. 
Barley, 137. 

composition of, 137. 
Beans, 142, 143. 
Beef, lean, 232. 

raw, 232. 

roasted, 232. 
Beef extracts, 234, 235. 
Beef juices, 234. 
Beer, 280. 

preservatives in, 282. 

varieties of, 281. 
Beet sugar, 191. 

diffusion process, 191. 

history of manufacture, 191. 

manufacture of, 191, 192. 

production of, 192. 
Beets, 208. 
Beverages, 257. 

alcoholic, 257. 

non-alcoholic, 257. 
Bibliography, 323. 
Bituminous coal, 28. 
Bluing, 92. 



Bluing, aniline, 105. 

indigo, 103. 

Prussian blue, 104. 
Boiling water for disinfection, 113. 
Boneblack filters, 195, 201. 
Borax, use in cleaning, 93. 
Brandy, 284. 

use of, in baking, 155. 
Bread, 154. 

adulteration, 177. 

aerated, 156. 

alum in, 177, 178. 

analysis of, 173. 

baking of, 169, 170. 

brown, 176. 

copper sulfate in, 177. 

fermentation of, 170. 

food value of, 174, 175. 

fresh, 172. 

loss in baking, 170. 

making without yeast, 155. 

not raised by fermentation, 154. 

raised by fermentation, 165. 

raising of, 169. 

stale, 172, 176. 

white, 175. 

why bad, 176, 177. 
Breakfast foods, 181. 

analysis of, 182. 

value of, 183. 
Burners and lamps, 58. 
Burners for gas, 31. 
Burning fluid, 50. 
Butter, composition of, 253. 

" Process, "254. 

"Renovated," 254. 

structure of, 253. 
Butter color, test for, 256. 
Butter fat, composition of, 243. 
Butterine, 224, 254. 



Cabbage, 208. 

Cafe au lait, 244. 

Caffein, 264. 

Calcium hypochlorite, 113. 

Calories, 310, 313, 314. 

Calorimeter, 313, 314. 

Camphene, 50. 



INDEX 



335 



Candle flame, 47. 
Candles, 48. 

dipped and molded, 49. 
Cane sugar, 187. 

properties of, 197. 
Cane sugar group, 124. 
Canned fruits* 297. 

iron in, 300. 

metals in, 300. 

methods adapted, 297. 

testing of, 300. 
Caramel in vinegar, 294. 
Carbohydrate, 124. 
Carbolic acid for disinfection, 111. 
Carbon, burning of, 24. 
Carbon dioxid, 9. 

amount in air, 9. 

cause of bad effects, 10. 

determination of, in air, 11. 

effect of, on system, 10. 

effect on a candle flame, 11. 

in closed rooms, 10. 

properties of, 9. 

source of, 9. 
Carbon monoxid, 13. 

presence in air, 14. 
Carrots, 217. 
Casein in milk, 245, 246. 
Cassava, 141. 
Catsup, 210. 
Cauliflower, 208. 
Celery, 209. 
Cellulose, 126. 

action of chemicals on, 126. 

basis of fuels, 24. 

digestibility of, 126. 
Cellulose group, 124. 
Centrifugal, 190, 195. 

use of, 190. 
Charcoal, 26. 

deodorizer, 109. 

methods of making, 26, 27. 
Cheese, 250. 

coloring of, 251. 

decay of, 252. 

falsification of, 253. 

food value of, 252. 

tyrotoxicon in, 252. 
Cheeses, 251. 



Cheeses, analyses of, 252. 

different varieties, 251. 
Chestnuts, 42, 226. 
ChevreuFs researches, 101. 
Chittenden, experiments by, 318. 
Chlorid of lime for disinfection, 113. 
Chlorin in water, 71. 
Chocolate, 265, 267, 268. 

action on system, 267. 

analyses, 266. 

food value, 268. 

manufacture of, 267. 

sweet, 268. 
Cholera epidemic in Messina, 75. 
Chondrin, 230. 
Cider, 278. 

adulteration of, 279. 

manufacture of, 278. 

preservation of, 279. 
Cinnamon, 289. 
City water supplies, 73. 
Cleaning, 92. 
Cleaning agents, 92. 

action of, 92. 
Cleaning powders, 92. 
Cloves, 289. 
Coal, 28. 

analyses of, 29. 

anthracite, 28. 

bituminous, 28. 

cannel, 28. 

lignite, 28. 

semianthracite, 28. 

semibituminous, 28. 
Cocoa, 265. 

amount imported, 267. 

analyses of, 266. 

cultivation of, 265. 

fat, 267. 

nibbs, 267. 

preparation of, 266. 

shells, 267. 

soluble, 267. 
Cocoa butter, 267. 
Cocoanut, oil of, 224. 
Cocoanuts, 227. 
Coffee, 262. 

action on system, 269. 

adulteration of, 264. 



336 



INDEX 



Coffee, amount imported, 267. 

analyses of, 263. 

caffein, 264. 

cultivation of, 262. 

history of, 223. 

preparation, 263. 

preparation of beverage, 268. 

roasting, 263. 

source of, 265. 

substitutes, 265. 
Coke, 29. 
Cola, 268. 

action on the system, 268. 
Collagen, 230. 

Coloring food products, 306. 
Combustion, complete and incom- 
plete, 24. 
Compound flour, 178. 
Condensed milk, 248. 

composition of normal, 248. 

food value of, 249. 

manufacture of, 248. 
Condiments, 288. 
Consumption, prevalence of, 40. 
Cooking of eggs, 240. 

of food, 121. 

right methods of, 311. 
Copper in foods, 207. 

sulfate for disinfectant, 112. 

sulfate in bread, 177. 

tests for, 307. 
Corn, 134. 

canned, 298. 

composition of, 134. 
Corn meal, 135. 

comparative value of, 135. 
Corn sirup, 200. 
Cornstarch, 146. 
Corrosive sublimate, 115. 

solution of, 115. 
Cost of food, 311. 
Cottolene, 224, 226. 
Cottonseed oil, 224. 
Cottosuet, 226. 
Cracker baking, 171. 
Crackers, 174. 
Cream, dried, 249. 

raising of, 244. 

ripening of, 253. 



Cream of tartar, 273, 274. 

use in baking, 257. 
Cream of tartar baking powders, 
158, 159. 

composition of, 159. 
Creatin, 231. 

Cremation to destroy refuse, 90. 
Creosote for disinfection, 111. 
Crowd poisoning, 40. 
Crumb and crust, 174. 

analyses of, 174. 

D 

Defecation of sugar, 195. 
Delicacy of sense of taste, 118. 
Dextrin, 148, 280. 

action of acids on, 199. 

made from starch, 199. 

properties of, 149. 
Dextrose, 199, 246. 
Diet, mixed, value of, 119, 120. 
Dietaries, 312, 315. 

estimation of, 315. 

history of investigation, 312, 313. 

in common use, 316. 

standard (Atwater), 317. 
Diffusion process, 199. 
Dilution, purification of water sup- 
plies by, 79. 
Disinfection, boiling water for, 113. 

calcium hypochlorite for, 113. 

chlorid of lime for, 113. 

copper sulfate for, 112. 

corrosive sublimate for, 115. 

creosote for, 111. 

formaldehyde for, 114. 

hydrogen peroxid for, 112. 

iron sulfate for, 112. 

mercuric chlorid for, 115. 

potassium permanganate for, 112. 

sulfur dioxid for, 100. 

tests for, 107. 

zinc chlorid for, 112. 
Distillates from petroleum, 57. 
Distilled liquors, adulteration of, 

285. 
Drinking water and disease, 74. 
Dry air a purifier, 109. 



INDEX 



337 



Dry earth, a purifier, 109. 

heat for disinfection, 110. 

wood, 26. 
Dust in air, infectious diseases 
propagated, 19. 

methods of examination, 17, 18. 

number of colonies, 18. 
Dutch oven, 171. 

E 

Economy in preparation of food, 
308. 

of fuel, 311. 
Egg substitutes, 240. 
Egg yolk, composition of, 239. 
Egg white, composition of, 238. 
Eggs, 238. 

compared with meat, 239. 

cooking of, 240. 

desiccated, 239. 

food value of, 239. 

preservation of, 239. 

use of, in baking, 155. 
Elastin, 230. 
Electric lights, 60. 
Electricity used for heating, 38. 
Elements contained in the body, 

222. 
Emulsin, 227. 
Enzymes, 229. 
Ergot, 179. 

Evaporated milk, 248. 
Experience in selection of foods, 

119. 
Extract of beef, 234, 235. 
Extracts, flavoring, 221. 

F 

Fat, amount of, from animal 
sources, 234. 

amount in vegetables, 223. 

composition, 297. 

food value of, 224. 
Fats, cooking of, 233, 309. 

digestion of, 309. 

edible, 223. 

properties of, 223. 



Fats and oils, 49. 

composition of, 49. 
Fatty acid, separation of, 49. 
Fermentation, causes that affect, 
169. 

lactic, 246. 
Fibrin, 230. 
Filters, household, 82. 

Pasteur-Chamberland, 83. 

Worms and Fisher, 82. 
Filtration, 80. 

iron process, 82. 

mechanical, 80. 

sand, efficiency of, 81. 

sand gallery, 81. 
Fire, use of, to destroy germs, 

112. 
Fireplace, use of, 33, 34. 
Fish, 235, 236. 

analyses of, 236. 

cooking of, 236. 

preservation of, 236. 
Flash point of oils, 52. 

apparatus used, 52. 
Flavoring extracts, 281. 
Flour, 133. 

adulteration of, 177. 

compound, 178. 

ergot in, 179. 
Food, accessories, 288. 

borax in, 303. 

breakfast, 181. 

chemistry of, 117. 

cooking of, 121. 

cost of, 311. 

cost per day, 319. 

definition of, 177. 

indigestible material in, 122. 

preservation of, 288, 297, 298. 

skill in preparing, 119. 

suited to habit, age, etc., 120. 

use of, 117. 

varieties of, 120. 

wasted, 319, 320. 
Food products, cooking of, 306. 
Foods, albuminous, 309. 

animal, 228, 310. 

classification of, 123, 124, 229. 

cooking of, 309. 



338 



INDEX 



Foods, leguminous, cooking of, 310. 

nitrogenous, 228. 

predigested, 380, 382. 

synthetic, 121. 

vegetable, 310. 
Formaldehyde as a disinfectant, 
114. 

method of using, 114. 
Fruit sirups, 221. 
Fruits, 212. 

acidity of, 216. 

analysis of, 214. 

canning of, 299. 

cooking of, 218, 219. 

distribution of, 212. 

malic acid in, 273. 

ripening of, 212, 214, 215. 

starch in, 214. 

structure of, 212. 

sugar in, 215. 

sugar in (table), 273. 
Fuel, economy of, 311. 

value of, 314. 

wood as, 25. 
Fuels, 23. 

calorie, definition of, 23. 

calorific power of combustibles, 
23. 
Fungi, 210. 
Furnaces, hot air, 35. 

precautions in use of, 36. 
Fusel oil, 284. 

G 

Galacto-araban, 215, 216. 
Galactose, 199, 246. 
Garbage, disposal of, 90. 
Garlic, 210. 
Gas, 30. 

acetylene, 55. 

advantages of, 31. 

air, 54. 

artificial, 30. 

bi-producers of manufacture, 54. 

burners, 31. 

carbon, 54. 

coal, 53. 

composition of, 56. 



Gas, drilling wells, 30. 

fuels, 31. 

illuminating, 53. 

lights, incandescent, 59. 

methods of making, 53. 

natural and artificial, 30. 

natural, composition of, 32. 

Pintsch, 55. 

pressure for burning, 55. 

purification of, 54. 

water, 54. 
Gas burners for light or heat, 

48. 
Gas fights, Welsbach system, 59. 
Gases, poisonous, 21. 
Gasoline, 51. 

use of, 32. 
Germ flour, 175. 
Gin, 284. 
Ginger, 290. 
Globulin, 229. 
Glucose, 281. 

commercial, 200. 

composition of, 201. 

healthfulness of, 202. 

manufacture of, 200, 201. 

properties of, 202. 

sirups, 202. 

sweetness of, 202. 

use of, 202, 219. 
Glucose group, 225. 
Gluten, 148, 166. 

in flour, 173. 
Glycerin, 101. 

from soap, 98. 
Granulated sugar, 196. 
Grape sugar, 200, 201. 

composition of, 201. 

manufacture of, 201. 
Grapes, 273. 

cultivation of, 273. 

ripening of, 273. 
Grease, removal of, 93, 94. 
Greens, food value of, 208. 
Ground air, 20. 

compared with atmospheric air, 
20. 

effects on the system, 21. 

germs in air, 21. 



INDEX 



339 



Hamburg, Germany, epidemic of 

cholera in, 76. 
Hard water, 67. 

permanently, 67. 

temporarily, 67. 
Heat, means of obtaining, 33. 
Helium, discovery of, 3. 
Honey, 204. 

adulteration of, 205. 

composition of, 205. 

food value of, 205. 
Household wastes, 89. 

disposal of, 89, 90. 
Human body, compounds found in, 
123. 

composition of (table), 122. 
Hydrogen, 24. 

burning of, 24. 

peroxid, 15. 

sulfid in air, 14. 
Hydrogen peroxid as a disinfec- 
tant, 112. 



Iceland moss, 210. 
Incandescent gas lights, 59. 
Income necessary for subsistence, 

320. 
Indigo used in bluing, 303. 
Infants' foods, 174, 181. 

composition of, 181. 
Injurious trades, 20. 
Ink spots, removal of, 95. 
Inosite, 125. 
Introduction, xix. 
Inulin, 149. 
Invert sugar, 215. 
Investigations needed, 321. 
Iron sulfate as disinfectant, 112. 



Jams, adulteration of, 219, 220. 
Jams and jellies, 219. 
Jel!ie§ and jams, 219. 



K 

Kerosene, 51. 

purification of, 52. 
Koumiss, 244. 

L 

Lactalbumin, 246. 
Lactometer, 243. 
Lactose, 199. 
Lamps and burners, 58. 
Lard, compound, 226. 

kettle rendered, 225. 

leaf, 225. 

neutral, 225, 254. 

prime steamed, 225. 

refined, 225. 

scrap, 225. 

steam rendered, 224. 

stiffening of, 225. 
Lausen (Switzerland), typhoid fever 

in, 77. 
Leaven, 167. 

use of, 167. 
Leaves used as food, 208, 209. 
Lecithin, 230. 
Leeks, 210. 
Legumes, 142. 

composition of, 143. 

food value of, 143. 
Legumin, 143. 
Leguminous foods, cooking of, 310. 

digestibility of, 143. 
Lemon, extract of, 221, 222. 
Lentils, 142, 143. 
Lettuce, 149. 
Levulose, 204. 
Lichens, 210. 
Light, 46. 

candle flame, 47. 

early sources of, 48. 

source of, 46. 
Light-producing substances, 46. 
Light, ideal, 60. 
Lighting, 46. 

common methods of, 46. 
Liqueurs and cordials, 272, 285, 286. 
Liquors, distilled, 272, 283. 

fermented, 272. 

malt, 272. 



340 



INDEX 



Macaroni, 183. 

composition of, 184. 

food value of, 184. 
Mace, 290. 
Maize, 134. 

Malt, manufacture of, 280. 
Malt liquors, 281. 

analvses of, 281. 
Maltose. 199, 280. 

hydrolysis of, 199. 
Mantles, composition of, 59. 

life of, 59. 
Maple sugar, 192. 

adulteration of, 193. 
Mashing, 280. 
Masse cute, 190, 195. 
Mate, 261, 263. 
Meat, boning, 233. 

cooking of, 232, 233, 237. 

diseases, 236. 

effect of cooking on, 232. 

food value of, 231, 235. 

lean, 231. 

roasting, 233. 

stewing, 234. 

structure of, 231. 

varieties of, 235. 

water in, 234. 
Mercuric chlorid as a disinfectant, 

115. 
Messina, epidemic of cholera, 75. 
Metals, cleaning of, 96. 
Milk, 242. 

adulteration of, 249. 

albumin in, 246. 

ash of, 247. 

borax in, 250. 

casein in, 245, 246. 

changes produced, 247. 

condensed, 248. 

dried, 249. 

evaporated, 248. 

fat in, 243, 244. 

fore, 244. 

formaldehyde in, 250, 302. 

from different animals, 242. 



Milk, modified, 249. 

pasteurized, 248. 

proteids of, 246. 

souring of, 246. 

specific gravity of, 243. 

sterilized, 247. 

strippings, 244. 

total solids in, 244. 
Milk sugar, 199, 246. 

manufacture of, 246. 

properties of, 199. 
Milwaukee sewage system, 86. 
Mineral water, 64. 
Modified milk, 249. 
Molasses, 194. 
Moss, Carrageen, 210. 

Iceland, 210. 

Irish, 210. 
Mucin, 230. 
Muscovado sugar, 189. 
Mushrooms, 210. 

poisonous, 211. 
Must of wine, 274. 
Mustard, adulteration of, 291. 

black, 290. 

white, 290. 
Mutton, 235. 
Myosin, 229, 231, 291. 



N 

Natural gas, 32. 
Nitric acid in air, 14. 
Nitrites and nitrates, 71. 

significance of, 71. 
Nitrites in water, 70. 
Nitrogen, properties of, 6. 
Nitrogenous foods, 228. 

classification of, 229. 

use of, 228. 
Non-alcoholic beverages, compari- 
son of, 269. 

per capita consumption, 257. 

use of, 270. 
Nuclein, 230. 
Nutmegs, 290. 
Nuts, food value of, 226, 

analyses of, 226. 



INDEX 



341 



Oatmeal, analyses of, 135. 

food value of, 136. 
Oats, 135. 

Offensive gases, 121. 
Oil, cottonseed, 224. 

petroleum, 51. 
Oil of cocoanut, 224. 
Oils, edible, 223. 

fire test of, 52. 

flash point, 52. 
Oleomargarin, 254. 

manufacture of, 254. 

production of, 255. 

tax on, 255. 

tests for, 256. 
Oleo-oil, manufacture of, 254, 255. 
Onions, 210. 

Organic matter in water, 69. 
Oven, heat of, 171. 
Oxidation of water, 79. 
Oxygen, properties of, 6. 
Oysters, 236. 
Ozone, constitution of, 15. 

discovery of, 15. 

occurrence of, 15. 

test for, 15. 



Paint, solvents for, 93, 95. 
Paraffin, 50, 52. 
Paraguay tea, 261. 
Parasites in meat, 237. 
Parsnips, 207. 
Pasteurized milk, 248. 
Pea sausage, 144. 
Peanuts, 227. 
Peas, 142, 143. 

green, 144. 
Peat, 27. 

abundance of, 27. 

source of, 27. 
Pectin, 215. 
Pectose, 125, 215. 
Pectous bodies, 215. 
Pepper, 289. 
Pepsin, 231. 



Peptone, 229. 

Perry, 279. 

Petroleum distillates, 51. 

Phosphate powders, composition of, 

158, 160, 161. 
Physiological action of alcohol, 286, 

289. 
Pie plant, 209. 
Pintsch gas, 55. 
Plantain, 144. 
Plastering of wine, 277. 
Plymouth, Pennsylvania, epidemic 

of typhoid fever, 76. 
Polishing materials, 92, 93. 
Potassium permanganate, 112. 
Potatoes, 138. 

analysis of, 139. 

food value of, 139, 140. 

introduction of, 138, 139. 

structure of, 140. 

sweet, 140. 
Predigested foods, 180, 182. 
Preface, v. 

Preservation of food, 297, 298, 
299. 

history of, 297. 
Preserved food, metals in, 300. 
Preservatives, 219. 

effects on the system, 301, 302, 
303. 
Preservatives in foods, 301. 

in common use, 303. 
Process butter, detection of, 256. 
Proteids, 229. 
Proteoses, 229. 
Prussian blue, 104. 
Ptyalin, action of, 199. 
Purification of water supplies, 79. 

Q 
Quicklime for disinfection, 110. 

R 

Radiation, direct, 33. 
Radiation, indirect, 35. 

use of steam, 36. 
Ramsay and Rayleigh, discoveries 
of, 2. 



342 



INDEX 



Ration, ideal (table), 319. 
Reduction to destroy refuse, 90, 91. 
Refining sugar, 194, 195. 
Rennet, 246. 
Respiration, 39. 

air needed for, 41. 
Rhubarb, 209. 
Rice, 137. 

composition of, 138. 

food value of, 138. 

preparation of, 137. 
Richard's ideal ration, 319. 
River water, 62. 
Roots used as food, 207. 
Rum, 284. 
Rye, 136. 

composition of, 137. 
Rye flour, 136. 



S 



Saccharin, 186, 219. 

in foods, 304. 

tests for, 305. 
Sago, 141. 
Sake, 282. 
Salep, 142. 
Salt, 295. 

composition of, 295. 

production of, 295. 
Salt-rising process, 168. 
Sanitary analysis of water, 69. 
Saponification, 97, 98. 
Sauerkraut, 209. 
Scurvy, 237. 
Separator, use of, 244. 
Septic tank, 88. 
Sewage, composition of, 84, 85. 

definition of, 83, 84. 

disposal of, by dilution, 95, 96. 

precipitation of, 88. 

purification of, 85. 
Sewage disposal, 84. 

by chemical precipitation, 88. 

by intermittent filtration, 87. 

by irrigation, 87. 

by septic tank, 88. 
Shale oil, 50. 
Silver, cleaning of, 96. 



Sirup, maple, adulteration of, 192. 
Sirups, fruit, 221. 
Snow, use of, in baking, 155. 
Soap, 92. 

castile, 99. 

Chevreul's researches, 101. 

cocoanut oil, 99. 

economy in use of, 101. 

glycerin from, 101. 

hard, 101. 

lye, 100. 

manufacture of, 98. 

mottled, 98. 

sand, 100. 

soft, 100. 

theory of action, 101. 

toilet, 100. 

transparent, 100. 

yellow, 99. 
Soap-making materials, 91. 
Soap solution, 68. 
Sodium bicarbonate, use of, in 

baking, 155, 157. 
Sodium sulfite in fruits, 304. 
Softening of water by Clarke's 

process, 82. 
Sorghum sugar, 193. 
Sour milk, 246. 

use of, in baking, 157. 
Soy beans, 142. 
Spaghetti, 183. 
Spices, 288. 

Stalks, used as food, 208, 209. 
Standard dietaries, 217, 218. 
Starch, 128. 

adulteration of, 142. 

chemical properties of, 150. 

detection of source of, 150. 

hydrolysis of, 152. 

in cereals, 128. 

in fruits, 129, 214. 

in legumes, 129. 

in nuts, 129. 

in roots, 129. 

in wheat, 129. 

making from wheat, 147. 

methods for making, 146, 147. 

physical properties, 149, 150. 

sources of, 128. 



INDEX 



343 



Starchy foods, cooking of, 308. 

Steam for heating, 36. 

Steam heat for disinfection, 113. 

Steamer, use of, 311. 

Sterilized milk, 247. 

Stoves, precautions in use of, 35. 

use of, 34. 

ventilation with, 34. 
Subsistence, income used, 320. 
Sucrose, 187. 
Sugar, maple, 192. 

adulteration of, 193. 

manufacture of, 193. 

sorghum, 193. 
Sugar, powdered, 196. 

production of, 190. 

properties of, 197. 

refining, 194, 195. 

spots, removal of, 95. 

sources of, 187. 

triple effect evaporators, 189. 

use of boneblack, 189. 
Sugar beets, 190. 
Sugar cane, cultivation of, 187, 188. 

making sugar from, 188. 
Sugar making, 188, 189. 
Sugars, analyses of, 198. 

adulteration of, 194, 197. 

boiling, 189. 

classification of, 185, 186. 

consumption of, 186. 

cut, 197. 

filtration of, 195. 

food value of, 198, 199. 

granulated, 196. 

history of, 185. 

in fruits, 215. 

in fruits (table), 293. 

inversion of, 190, 193, 204. 
Sunlight as a disinfectant, 109. 
Sweet potatoes, 140. 

composition of, 140. 
Synthetic foods, 121. 



Table of contents, vii. 
Tallow, 49. 
Tannin, in tea, 261. 



Tannin, in coffee, 264. 
Tapioca, 141. 

preparation of, 141. 
Tartrate baking powders, 159. 
Taste, delicacy of the sense, 118. 
Taste and smell, 118. 

use of, 118. 
Tea, 258. 

action on the system, 259. 

adulteration of, 259. 

amount imported, 257. 

analyses of, 260. 

black vs. green, 258. 

coffee leaf, 262. 

cultivation of, 258. 

green, 258. 

history of cultivation, 258. 

Indian, 259. 

Japan, 258. 

lye, 260. 

Paraguay, 261. 

preparation, 258. 

preparation of beverage, 260. 

spurious, 259. 

tannin, 261. 

thein, 261. 
Tees Valley, epidemic of typhoid 

fever in, 75. 
Theobromin, 267. 
Toadstools, 210, 211. 
Tomatoes, 210. 

canned, 298. 
Tous les Mois, 142. 
Trades, injurious, 20. 
Truffles, 211. 
Turnips, 207. 

Typhoid fever epidemic in Tees 
VaUey, 75. 

in Lausen, Switzerland, 77. 
Tyrotoxicon in cheese, 252. 

U 

Ultramarine, 104. 
use of, 196. 

V 

Vacuum pan, 189, 195, 201. 
Vanilla, extract of, 221. 
Veal, 235. 



344 



INDEX 



Ventilation, 33, 38. 

by natural or forced draft, 42. 

conditions necessary, 42. 

exhaust fans, 43. 

importance of, 38, 39. 

open grates, 44. 

special devices, 44. 
Vermicelli, 183. 
Vinegar, 291. 

acid of, 293. 

caramel in, 294. 

cider, 293. 

fermentation in, 292. 

imitation, 293. 

materials used, 292. 

quick process, 292, 293. 

wine, 293. 
Voit, experiments by, 315. 

W 

Wall paper, arsenic in, 19. 
Washing soda, 101. 

use of, 102, 103. 
Waste of food, 320, 321. 
Water, 61. 

analyses of city supplies, 72. 

chlorin in, 71. 

cistern, 61. 

drinking and disease, 74. 

effect of freezing on, 73. 

nitration and softening, 80. 

filtration by sand, 80. 

free ammonia in, 70. 

Hamburg (Germany), analyses 
of, 77. 

hard, 67. 

in air, 6, 7. 

in meat, 234. 

lake, 62. 

mineral, 64. 

mineral substances in, 64. 

mechanical filtration, 81. 

natural, 61. 

nitrates in, 61. 

nitrites in, 70. 

organic matter in, 69. 

oxidation of, 79. 

polluted by sewage, 74. 



Water, rain, 62. 

sanitary analysis of, 69. 

softening, Clarke's process, 82. 

spring, 62. 

storage, 63. 

turbid, 74. 

well, 63. 
Water, hot, for heating, 37. 

advantage over steam, 37. 
Water supplies, 79. 

purification of, 79. 

purification by dilution, 79. 
Waters, hard, 67. 

disadvantages of, 68. 
Well water, 63. 

artesian, 63, 64. 

impurities in, 63. 

wells, domestic, dangers of, 63. 
Welsbach lights, 59. 
Wheat, 130. 

proteids of, 130. 

Russian, 131. 

starch in, 147. 

structure of grain, 130. 

varieties of, 130. 
Wheat flour, 131. 

analyses of, 131, 132, 133. 

patent, 134. 

value of, 132. 
Whey, 246. 

use of, 199. 
Whisky, 284. 
White bread, 175. 
Wine, 273. 

adulteration of, 277. 

aging of, 274. 

analyses of, 275, 276. 

chaptalising of, 277. 

classification of, 276. 

manufacture of, 274. 

old, 275. 

plastering, 277. 

still, 276. 

tannin in, 275. 
Wood, ash of, 26. 

drying of, 26. 

seasoning of, 26. 

water in, 25. 
Wood as fuel, 25. 



INDEX 



345 



Wort, 280. 

Wounds, lacerated, care of, 115. 



Xanthin, 231. 
Xyloiden, 153. 



X 



Yeast, 165, 280. 
cakes, 167. 



Yeast, compressed, 166. 
cultivation of, 166. 
domestic, 167. 
history of use, 166. 
in beer, 280, 281. 
use of, 165. 



Zinc chlorid for disinfection, 112. 



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